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DOE OSTI2020

Materials Data on KHf6CCl15 by Materials Project

KHf6CCl15 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. K is bonded in a distorted q6 geometry to ten Cl atoms. There are a spread of K–Cl bond distances ranging from 3.36–3.52 Å. There are five inequivalent Hf sites. In the first Hf site, Hf is bonded to one C and five Cl atoms to form a mixture of corner and edge-sharing HfCCl5 octahedra. The corner-sharing octahedral tilt angles are 0°. The Hf–C bond length is 2.22 Å. There are four shorter (2.50 Å) and one longer (2.66 Å) Hf–Cl bond lengths. In the second Hf site, Hf is bonded to one C and five Cl atoms to form a mixture of corner and edge-sharing HfCCl5 octahedra. The corner-sharing octahedra tilt angles range from 0–43°. The Hf–C bond length is 2.23 Å. There are a spread of Hf–Cl bond distances ranging from 2.50–2.74 Å. In the third Hf site, Hf is bonded to one C and five Cl atoms to form a mixture of corner and edge-sharing HfCCl5 octahedra. The corner-sharing octahedra tilt angles range from 1–48°. The Hf–C bond length is 2.27 Å. There are a spread of Hf–Cl bond distances ranging from 2.51–2.66 Å. In the fourth Hf site, Hf is bonded to one C and five Cl atoms to form a mixture of corner and edge-sharing HfCCl5 octahedra. The corner-sharing octahedral tilt angles are 0°. The Hf–C bond length is 2.22 Å. There are four shorter (2.53 Å) and one longer (2.64 Å) Hf–Cl bond lengths. In the fifth Hf site, Hf is bonded to one C and five Cl atoms to form a mixture of corner and edge-sharing HfCCl5 octahedra. The corner-sharing octahedra tilt angles range from 0–48°. The Hf–C bond length is 2.27 Å. There are a spread of Hf–Cl bond distances ranging from 2.51–2.66 Å. There are two inequivalent C sites. In the first C site, C is bonded in an octahedral geometry to six Hf atoms. In the second C site, C is bonded in an octahedral geometry to six Hf atoms. There are eleven inequivalent Cl sites. In the first Cl site, Cl is bonded in a rectangular see-saw-like geometry to two equivalent K and two equivalent Hf atoms. In the second Cl site, Cl is bonded in a distorted square co-planar geometry to two equivalent K and two Hf atoms. In the third Cl site, Cl is bonded in a 3-coordinate geometry to one K and two Hf atoms. In the fourth Cl site, Cl is bonded in an L-shaped geometry to two equivalent Hf atoms. In the fifth Cl site, Cl is bonded in an L-shaped geometry to two equivalent Hf atoms. In the sixth Cl site, Cl is bonded in an L-shaped geometry to two equivalent Hf atoms. In the seventh Cl site, Cl is bonded in an L-shaped geometry to two equivalent Hf atoms. In the eighth Cl site, Cl is bonded in a 3-coordinate geometry to one K and two Hf atoms. In the ninth Cl site, Cl is bonded in a bent 120 degrees geometry to two Hf atoms. In the tenth Cl site, Cl is bonded in a 3-coordinate geometry to one K and two Hf atoms. In the eleventh Cl site, Cl is bonded in a 3-coordinate geometry to one K and two Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf6Cr5Si7 by Materials Project

Hf6Cr5Si7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are six inequivalent Hf sites. In the first Hf site, Hf is bonded in a 7-coordinate geometry to two equivalent Cr and seven Si atoms. Both Hf–Cr bond lengths are 2.98 Å. There are a spread of Hf–Si bond distances ranging from 2.69–2.83 Å. In the second Hf site, Hf is bonded in a 7-coordinate geometry to two equivalent Cr and seven Si atoms. Both Hf–Cr bond lengths are 2.98 Å. There are a spread of Hf–Si bond distances ranging from 2.78–2.85 Å. In the third Hf site, Hf is bonded in a 6-coordinate geometry to three Cr and six Si atoms. There are two shorter (2.85 Å) and one longer (2.96 Å) Hf–Cr bond lengths. There are a spread of Hf–Si bond distances ranging from 2.66–2.84 Å. In the fourth Hf site, Hf is bonded in a 6-coordinate geometry to two equivalent Cr and six Si atoms. Both Hf–Cr bond lengths are 2.83 Å. There are a spread of Hf–Si bond distances ranging from 2.66–2.83 Å. In the fifth Hf site, Hf is bonded in a 10-coordinate geometry to five Cr and five Si atoms. There are a spread of Hf–Cr bond distances ranging from 2.94–3.07 Å. There are a spread of Hf–Si bond distances ranging from 2.79–2.95 Å. In the sixth Hf site, Hf is bonded to seven Si atoms to form distorted HfSi7 pentagonal bipyramids that share corners with four equivalent CrHf5Cr3Si4 cuboctahedra, corners with two equivalent HfSi7 pentagonal bipyramids, and edges with two equivalent HfSi7 pentagonal bipyramids. There are a spread of Hf–Si bond distances ranging from 2.67–2.89 Å. There are three inequivalent Cr sites. In the first Cr site, Cr is bonded in a 7-coordinate geometry to one Cr and six Si atoms. The Cr–Cr bond length is 2.42 Å. There are a spread of Cr–Si bond distances ranging from 2.44–2.66 Å. In the second Cr site, Cr is bonded in a 12-coordinate geometry to four Hf, two equivalent Cr, and three Si atoms. Both Cr–Cr bond lengths are 2.38 Å. There are one shorter (2.36 Å) and two longer (2.42 Å) Cr–Si bond lengths. In the third Cr site, Cr is bonded to five Hf, three Cr, and four Si atoms to form distorted CrHf5Cr3Si4 cuboctahedra that share corners with two equivalent CrHf5Cr3Si4 cuboctahedra, corners with two equivalent HfSi7 pentagonal bipyramids, and faces with two equivalent CrHf5Cr3Si4 cuboctahedra. There are one shorter (2.53 Å) and one longer (2.56 Å) Cr–Cr bond lengths. There are a spread of Cr–Si bond distances ranging from 2.44–2.50 Å. There are six inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to five Hf and four Cr atoms. In the second Si site, Si is bonded in a 9-coordinate geometry to five Hf and four equivalent Cr atoms. In the third Si site, Si is bonded in a 10-coordinate geometry to seven Hf, one Cr, and two equivalent Si atoms. There are one shorter (2.50 Å) and one longer (2.59 Å) Si–Si bond lengths. In the fourth Si site, Si is bonded in a 9-coordinate geometry to four Hf and five Cr atoms. In the fifth Si site, Si is bonded in a 9-coordinate geometry to five Hf and four Cr atoms. In the sixth Si site, Si is bonded in a 9-coordinate geometry to five Hf and four Cr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Hf–N bond distances ranging from 2.08–2.20 Å. There are one shorter (2.11 Å) and two longer (2.21 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–59°. There are a spread of Hf–N bond distances ranging from 2.07–2.21 Å. There are one shorter (2.27 Å) and one longer (2.29 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.09–2.18 Å. There are one shorter (2.28 Å) and one longer (2.30 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.22 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.20 Å. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Hf–N bond distances ranging from 2.09–2.19 Å. There are a spread of Hf–O bond distances ranging from 2.14–2.21 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.12–2.24 Å. There are one shorter (2.20 Å) and one longer (2.23 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.11–2.19 Å. There are one shorter (2.23 Å) and one longer (2.25 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.27 Å. There are one shorter (2.11 Å) and one longer (2.25 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.12–2.23 Å. The Hf–O bond length is 2.24 Å. In the tenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 55–57°. There are a spread of Hf–N bond distances ranging from 2.09–2.18 Å. There are one shorter (2.26 Å) and one longer (2.28 Å) Hf–O bond lengths. In the eleventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.09–2.18 Å. There are one shorter (2.22 Å) and one longer (2.28 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.14–2.25 Å. The Hf–O bond length is 2.21 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.12–2.24 Å. There are one shorter (2.15 Å) and one longer (2.19 Å) Hf–O bond lengths. In the fourteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.23 Å. The Hf–O bond length is 2.31 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.22 Å. There are one shorter (2.20 Å) and one longer (2.25 Å) Hf–O bond lengths. In the sixteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.12–2.22 Å. There are one shorter (2.13 Å) and one longer (2.20 Å) Hf–O bond lengths. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 tetrahedra, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.22 Å. There are one shorter (2.20 Å) and one longer (2.22 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.09–2.17 Å. There are one shorter (2.22 Å) and one longer (2.27 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.12–2.25 Å. There are one shorter (2.11 Å) and one longer (2.24 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.09–2.17 Å. There are one shorter (2.26 Å) and one longer (2.27 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of corner and edge-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.11–2.22 Å. The Hf–O bond length is 2.29 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with five HfN5O octahedra, a cornercorner with one HfN4O2 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.08–2.21 Å. There are one shorter (2.22 Å) and one longer (2.29 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted corner and edge-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 48–57°. There are a spread of Hf–N bond distances ranging from 2.13–2.18 Å. There are a spread of Hf–O bond distances ranging from 2.11–2.18 Å. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.13–2.22 Å. There are one shorter (2.13 Å) and one longer (2.21 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.13–2.21 Å. There are one shorter (2.15 Å) and one longer (2.19 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Hf–N bond distances ranging from 2.15–2.19 Å. There are one shorter (2.16 Å) and one longer (2.18 Å) Hf–O bond lengths. In the eleventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.08–2.20 Å. There are one shorter (2.23 Å) and one longer (2.31 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted corner and edge-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.22 Å. The Hf–O bond length is 2.29 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.11–2.29 Å. There are one shorter (2.13 Å) and one longer (2.24 Å) Hf–O bond lengths. In the fourteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of corner and edge-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.08–2.18 Å. There are a spread of Hf–O bond distances ranging from 2.15–2.25 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN5O octahedra, and an edgeedge with one HfN4O2 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.09–2.15 Å. There are one shorter (2.29 Å) and one longer (2.32 Å) Hf–O bond lengths. In the sixteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 48–58°. There are a spread of Hf–N bond distances ranging from 2.12–2.22 Å. There are one shorter (2.20 Å) and one longer (2.21 Å) Hf–O bond lengths. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OH

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to two N3- and four O2- atoms to form HfN2O4 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are one shorter (2.07 Å) and one longer (2.09 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.12–2.22 Å. In the second Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are one shorter (2.13 Å) and two longer (2.15 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.10–2.21 Å. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Hf–N bond distances ranging from 2.13–2.22 Å. There are one shorter (2.13 Å) and one longer (2.19 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–N bond distances ranging from 2.07–2.17 Å. There are one shorter (2.31 Å) and one longer (2.38 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Hf–N bond distances ranging from 2.09–2.30 Å. There are one shorter (2.19 Å) and one longer (2.22 Å) Hf–O bond lengths. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.14–2.19 Å. There are one shorter (2.13 Å) and one longer (2.19 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.11–2.21 Å. The Hf–O bond length is 2.28 Å. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 49–59°. There are a spread of Hf–N bond distances ranging from 2.10–2.21 Å. There are one shorter (2.20 Å) and one longer (2.27 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 52–54°. There are a spread of Hf–N bond distances ranging from 2.08–2.18 Å. There are one shorter (2.23 Å) and one longer (2.31 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.11–2.22 Å. The Hf–O bond length is 2.32 Å. In the eleventh Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.21 Å. There are one shorter (2.11 Å) and two longer (2.21 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.10–2.20 Å. The Hf–O bond length is 2.35 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.09–2.17 Å. There are one shorter (2.24 Å) and one longer (2.28 Å) Hf–O bond lengths. In the fourteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Hf–N bond distances ranging from 2.11–2.21 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.21 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–N bond distances ranging from 2.13–2.24 Å. The Hf–O bond length is 2.23 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.12–2.26 Å. The Hf–O bond length is 2.21 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with three OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Hf4+ a

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Hf–N bond distances ranging from 2.11–2.24 Å. There are one shorter (2.12 Å) and one longer (2.23 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–N bond distances ranging from 2.12–2.17 Å. There are one shorter (2.23 Å) and one longer (2.25 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.09–2.20 Å. There are one shorter (2.18 Å) and one longer (2.29 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.13–2.26 Å. There are one shorter (2.12 Å) and one longer (2.21 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.07–2.13 Å. There are a spread of Hf–O bond distances ranging from 2.18–2.28 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 54–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.17 Å. Both Hf–O bond lengths are 2.27 Å. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.09–2.17 Å. There are one shorter (2.26 Å) and one longer (2.27 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.10–2.19 Å. There are one shorter (2.23 Å) and one longer (2.27 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.18 Å. There are one shorter (2.24 Å) and one longer (2.26 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are one shorter (2.08 Å) and three longer (2.16 Å) Hf–N bond lengths. There are one shorter (2.20 Å) and one longer (2.32 Å) Hf–O bond lengths. In the eleventh Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Hf–N bond distances ranging from 2.13–2.20 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.16 Å. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.13–2.29 Å. The Hf–O bond length is 2.22 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Hf–N bond distances ranging from 2.10–2.27 Å. There are one shorter (2.19 Å) and one longer (2.21 Å) Hf–O bond lengths. In the fourteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.23 Å. The Hf–O bond length is 2.22 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Hf–N bond distances ranging from 2.10–2.16 Å. There are a spread of Hf–O bond distances ranging from 2.14–2.21 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Hf–N bond distances ranging from 2.12–2.23 Å. The Hf–O bond length is 2.32 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with eight NHf4 trigonal pyramids, and edges with four OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, edges with three NHf4 tetrahedra, and an edgeedge with one OHf4 trigonal pyramid. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fifth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with five OHf4 trigonal

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with four HfN4O2 octahedra, corners with two HfN3O3 pentagonal pyramids, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Hf–N bond distances ranging from 2.08–2.21 Å. There are one shorter (2.11 Å) and two longer (2.20 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with five HfN4O2 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–N bond distances ranging from 2.12–2.18 Å. There are one shorter (2.22 Å) and one longer (2.24 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.09–2.17 Å. There are one shorter (2.29 Å) and one longer (2.31 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Hf–N bond distances ranging from 2.13–2.27 Å. There are one shorter (2.14 Å) and one longer (2.24 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with five HfN3O3 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.24 Å. There are one shorter (2.19 Å) and one longer (2.21 Å) Hf–O bond lengths. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.18 Å. There are one shorter (2.26 Å) and one longer (2.27 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with five HfN4O2 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.08–2.20 Å. There are one shorter (2.25 Å) and one longer (2.28 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra, edges with four HfN4O2 octahedra, and edges with two HfN3O3 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.10–2.21 Å. There are one shorter (2.24 Å) and one longer (2.25 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with four HfN3O3 octahedra, corners with two HfN3O3 pentagonal pyramids, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Hf–N bond distances ranging from 2.09–2.18 Å. There are one shorter (2.21 Å) and one longer (2.28 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra, edges with four HfN4O2 octahedra, and edges with two HfN3O3 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Hf–N bond distances ranging from 2.12–2.24 Å. The Hf–O bond length is 2.32 Å. In the eleventh Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with four HfN4O2 octahedra, corners with two HfN3O3 pentagonal pyramids, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–53°. There are a spread of Hf–N bond distances ranging from 2.12–2.21 Å. There are a spread of Hf–O bond distances ranging from 2.12–2.16 Å. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Hf–N bond distances ranging from 2.14–2.26 Å. The Hf–O bond length is 2.23 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 pentagonal pyramids that share corners with five HfN3O3 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Hf–N bond distances ranging from 2.07–2.18 Å. There are a spread of Hf–O bond distances ranging from 2.15–2.22 Å. In the fourteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with five HfN3O3 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.13–2.23 Å. The Hf–O bond length is 2.22 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 pentagonal pyramids that share corners with five HfN3O3 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are one shorter (2.09 Å) and two longer (2.16 Å) Hf–N bond lengths. There are two shorter (2.15 Å) and one longer (2.23 Å) Hf–O bond lengths. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra, edges with four HfN4O2 octahedra, and edges with two HfN3O3 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.13–2.22 Å. The Hf–O bond length is 2.30 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with seven NHf4 trigonal pyramids, and edges with four OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, edges with three NHf4 tetrahedra, and an edgeedge with one OHf4 trigonal pyramid. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, edges with two NHf4 tetrahedra, and edges with two NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges wit

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Hf–N bond distances ranging from 2.08–2.19 Å. There are one shorter (2.23 Å) and one longer (2.29 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.10–2.19 Å. There are one shorter (2.21 Å) and one longer (2.25 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.08–2.17 Å. There are one shorter (2.29 Å) and one longer (2.31 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN5O octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.23 Å. There are a spread of Hf–O bond distances ranging from 2.11–2.23 Å. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Hf–N bond distances ranging from 2.08–2.21 Å. There are a spread of Hf–O bond distances ranging from 2.11–2.23 Å. In the sixth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.20 Å. The Hf–O bond length is 2.27 Å. In the seventh Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form HfN3O3 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are two shorter (2.07 Å) and one longer (2.12 Å) Hf–N bond lengths. There are one shorter (2.21 Å) and two longer (2.26 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.12–2.25 Å. The Hf–O bond length is 2.34 Å. In the ninth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Hf–N bond distances ranging from 2.10–2.23 Å. The Hf–O bond length is 2.30 Å. In the tenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Hf–N bond distances ranging from 2.12–2.20 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.17 Å. In the eleventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.10–2.18 Å. There are one shorter (2.26 Å) and one longer (2.27 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.15–2.23 Å. The Hf–O bond length is 2.22 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Hf–N bond distances ranging from 2.06–2.20 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.24 Å. In the fourteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN5O octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Hf–N bond distances ranging from 2.16–2.18 Å. There are one shorter (2.16 Å) and one longer (2.17 Å) Hf–O bond lengths. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Hf–N bond distances ranging from 2.13–2.23 Å. The Hf–O bond length is 2.22 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.12–2.24 Å. There are one shorter (2.18 Å) and one longer (2.21 Å) Hf–O bond lengths. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with two NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 tetrahedra, and edges with two NHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form OHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form OHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.24 Å. There are one shorter (2.18 Å) and one longer (2.27 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.18 Å. There are one shorter (2.23 Å) and one longer (2.26 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.19 Å. There are one shorter (2.23 Å) and one longer (2.28 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.08–2.20 Å. There are one shorter (2.24 Å) and one longer (2.29 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–53°. There are a spread of Hf–N bond distances ranging from 2.13–2.16 Å. There are a spread of Hf–O bond distances ranging from 2.09–2.21 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–54°. There are a spread of Hf–N bond distances ranging from 2.13–2.21 Å. There are one shorter (2.15 Å) and one longer (2.17 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.22 Å. There are one shorter (2.23 Å) and one longer (2.25 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–N bond distances ranging from 2.07–2.14 Å. There are two shorter (2.19 Å) and one longer (2.30 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.13–2.23 Å. The Hf–O bond length is 2.24 Å. In the tenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.11–2.22 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.19 Å. In the eleventh Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 53–55°. There are a spread of Hf–N bond distances ranging from 2.11–2.25 Å. The Hf–O bond length is 2.31 Å. In the twelfth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.08–2.18 Å. There are one shorter (2.18 Å) and one longer (2.34 Å) Hf–O bond lengths. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Hf–N bond distances ranging from 2.09–2.20 Å. There are one shorter (2.26 Å) and one longer (2.28 Å) Hf–O bond lengths. In the fourteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.15–2.20 Å. There are one shorter (2.16 Å) and one longer (2.18 Å) Hf–O bond lengths. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.12–2.22 Å. The Hf–O bond length is 2.28 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–59°. There are a spread of Hf–N bond distances ranging from 2.11–2.19 Å. There are one shorter (2.20 Å) and one longer (2.24 Å) Hf–O bond lengths. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with two OHf4 trigonal pyramids, corners with ten NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two OHf4 trigonal pyramids, corners with ten NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two OHf4 trigonal pyramids, corners with ten NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two OHf4 trigonal pyramids, corners with ten NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges wi

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are two shorter (2.11 Å) and one longer (2.22 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.14–2.22 Å. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–60°. There are a spread of Hf–N bond distances ranging from 2.09–2.23 Å. There are one shorter (2.20 Å) and one longer (2.27 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.16 Å. Both Hf–O bond lengths are 2.26 Å. In the fourth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are one shorter (2.07 Å) and two longer (2.10 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.20–2.29 Å. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form HfN3O3 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–60°. There are a spread of Hf–N bond distances ranging from 2.07–2.18 Å. There are a spread of Hf–O bond distances ranging from 2.15–2.26 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.15–2.18 Å. There are one shorter (2.15 Å) and one longer (2.19 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Hf–N bond distances ranging from 2.14–2.19 Å. Both Hf–O bond lengths are 2.16 Å. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Hf–N bond distances ranging from 2.07–2.17 Å. There are one shorter (2.21 Å) and one longer (2.29 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are one shorter (2.08 Å) and two longer (2.13 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.10–2.29 Å. In the tenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–55°. There are a spread of Hf–N bond distances ranging from 2.12–2.26 Å. There are one shorter (2.13 Å) and one longer (2.25 Å) Hf–O bond lengths. In the eleventh Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.14–2.26 Å. The Hf–O bond length is 2.19 Å. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.13–2.20 Å. The Hf–O bond length is 2.26 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 54–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.23 Å. The Hf–O bond length is 2.29 Å. In the fourteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–55°. There are a spread of Hf–N bond distances ranging from 2.11–2.26 Å. Both Hf–O bond lengths are 2.16 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.24 Å. The Hf–O bond length is 2.33 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.12–2.22 Å. There are one shorter (2.22 Å) and one longer (2.25 Å) Hf–O bond lengths. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with two OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, and edges with four OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with two OHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded in a distorted rectangular see-saw-like geometry to four Hf4+ atoms. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and an edgeedge with one OHf4 trigonal pyramid. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two OHf4 trigon

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form HfN3O3 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Hf–N bond distances ranging from 2.09–2.13 Å. There are one shorter (2.19 Å) and two longer (2.23 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to two N3- and four O2- atoms to form a mixture of distorted corner and edge-sharing HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 50–53°. There are one shorter (2.11 Å) and one longer (2.14 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.09–2.20 Å. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN5O octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.14–2.22 Å. There are one shorter (2.13 Å) and one longer (2.21 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN5O octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.07–2.11 Å. There are a spread of Hf–O bond distances ranging from 2.19–2.30 Å. In the fifth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.09–2.29 Å. Both Hf–O bond lengths are 2.21 Å. In the sixth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 54–60°. There are a spread of Hf–N bond distances ranging from 2.10–2.20 Å. The Hf–O bond length is 2.33 Å. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.20 Å. There are one shorter (2.15 Å) and one longer (2.20 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.08–2.17 Å. There are one shorter (2.27 Å) and one longer (2.29 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted corner and edge-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are two shorter (2.11 Å) and one longer (2.19 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.13–2.20 Å. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN2O4 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.11–2.21 Å. The Hf–O bond length is 2.27 Å. In the eleventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 49–60°. There are a spread of Hf–N bond distances ranging from 2.10–2.24 Å. There are one shorter (2.21 Å) and one longer (2.24 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.13–2.21 Å. There are one shorter (2.16 Å) and one longer (2.24 Å) Hf–O bond lengths. In the thirteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted corner and edge-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.20 Å. The Hf–O bond length is 2.31 Å. In the fourteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Hf–N bond distances ranging from 2.08–2.21 Å. There are one shorter (2.17 Å) and one longer (2.33 Å) Hf–O bond lengths. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN2O4 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.13–2.24 Å. The Hf–O bond length is 2.21 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.14–2.25 Å. The Hf–O bond length is 2.20 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and an edgeedge with one OHf4 trigonal pyramid. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fourth O2- site, O2- is bond

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–55°. There are a spread of Hf–N bond distances ranging from 2.09–2.18 Å. There are one shorter (2.25 Å) and one longer (2.26 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.09–2.16 Å. There are one shorter (2.28 Å) and one longer (2.33 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.09–2.21 Å. There are one shorter (2.12 Å) and two longer (2.19 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.13–2.27 Å. There are one shorter (2.11 Å) and one longer (2.24 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.09–2.17 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.22 Å. In the sixth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 49–59°. There are a spread of Hf–N bond distances ranging from 2.08–2.12 Å. There are a spread of Hf–O bond distances ranging from 2.19–2.27 Å. In the seventh Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. All Hf–N bond lengths are 2.10 Å. There are a spread of Hf–O bond distances ranging from 2.21–2.24 Å. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.09–2.16 Å. There are one shorter (2.24 Å) and one longer (2.26 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of Hf–N bond distances ranging from 2.11–2.20 Å. There are two shorter (2.14 Å) and one longer (2.19 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.22 Å. The Hf–O bond length is 2.33 Å. In the eleventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.08–2.18 Å. There are one shorter (2.21 Å) and one longer (2.29 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.13–2.27 Å. The Hf–O bond length is 2.21 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–N bond distances ranging from 2.13–2.29 Å. The Hf–O bond length is 2.20 Å. In the fourteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–54°. There are a spread of Hf–N bond distances ranging from 2.12–2.20 Å. There are one shorter (2.14 Å) and one longer (2.21 Å) Hf–O bond lengths. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.12–2.23 Å. The Hf–O bond length is 2.25 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Hf–N bond distances ranging from 2.10–2.23 Å. The Hf–O bond length is 2.27 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with three OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 tetrahedra, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one OHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to fo

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–N bond distances ranging from 2.11–2.19 Å. There are one shorter (2.21 Å) and one longer (2.25 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of Hf–N bond distances ranging from 2.10–2.20 Å. There are a spread of Hf–O bond distances ranging from 2.12–2.20 Å. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.10–2.18 Å. There are one shorter (2.26 Å) and one longer (2.30 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.12–2.26 Å. Both Hf–O bond lengths are 2.21 Å. In the fifth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.09–2.18 Å. There are one shorter (2.27 Å) and one longer (2.28 Å) Hf–O bond lengths. In the sixth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted corner and edge-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Hf–N bond distances ranging from 2.09–2.20 Å. There are a spread of Hf–O bond distances ranging from 2.11–2.21 Å. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.24 Å. There are one shorter (2.17 Å) and one longer (2.21 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.19 Å. There are one shorter (2.25 Å) and one longer (2.27 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.09–2.18 Å. There are one shorter (2.24 Å) and one longer (2.26 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 54–57°. There are a spread of Hf–N bond distances ranging from 2.11–2.25 Å. The Hf–O bond length is 2.32 Å. In the eleventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 54–57°. There are a spread of Hf–N bond distances ranging from 2.11–2.20 Å. There are one shorter (2.24 Å) and one longer (2.25 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.14–2.25 Å. The Hf–O bond length is 2.21 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–59°. There are a spread of Hf–N bond distances ranging from 2.08–2.24 Å. There are one shorter (2.18 Å) and one longer (2.23 Å) Hf–O bond lengths. In the fourteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted corner and edge-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 49–54°. There are a spread of Hf–N bond distances ranging from 2.09–2.16 Å. There are two shorter (2.16 Å) and one longer (2.23 Å) Hf–O bond lengths. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.14–2.23 Å. The Hf–O bond length is 2.21 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.12–2.23 Å. There are one shorter (2.16 Å) and one longer (2.22 Å) Hf–O bond lengths. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, edges with two OHf4 tetrahedra, and edges with two NHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two OHf4 tetrahedra, corners with three NHf4 tetrahedra, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 tetrahedra, and edges with two NHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two OHf4 tetrahedra, corners with three NHf4 tetrahedra, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 tetrahedra, and edges with two NHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 tetrahedra, and edges with three NHf4 tetrahedra. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with three NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with three NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 tetrahedra, and edges with two NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with two NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one OHf4 tetrahedra, corners with two NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two OHf4 tetrahedra, corners with three NHf4 tetrahedra, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 te

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form HfN3O3 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN4O2 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.16 Å. There are a spread of Hf–O bond distances ranging from 2.14–2.21 Å. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–54°. There are a spread of Hf–N bond distances ranging from 2.13–2.23 Å. There are one shorter (2.15 Å) and one longer (2.23 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with five HfN3O3 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Hf–N bond distances ranging from 2.12–2.22 Å. There are one shorter (2.14 Å) and one longer (2.19 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.07–2.24 Å. There are one shorter (2.19 Å) and one longer (2.35 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 pentagonal pyramids that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 47–59°. There are a spread of Hf–N bond distances ranging from 2.06–2.19 Å. There are a spread of Hf–O bond distances ranging from 2.14–2.26 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with five HfN4O2 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.09–2.20 Å. There are one shorter (2.19 Å) and one longer (2.27 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Hf–N bond distances ranging from 2.14–2.20 Å. There are one shorter (2.14 Å) and one longer (2.22 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with five HfN3O3 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.21 Å. There are a spread of Hf–O bond distances ranging from 2.12–2.21 Å. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with five HfN4O2 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.08–2.19 Å. There are one shorter (2.26 Å) and one longer (2.28 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form HfN5O octahedra that share corners with five HfN4O2 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 54–60°. There are a spread of Hf–N bond distances ranging from 2.10–2.21 Å. The Hf–O bond length is 2.33 Å. In the eleventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN4O2 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 54–57°. There are a spread of Hf–N bond distances ranging from 2.15–2.19 Å. There are one shorter (2.14 Å) and one longer (2.18 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra, edges with five HfN4O2 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 50–60°. There are a spread of Hf–N bond distances ranging from 2.12–2.26 Å. The Hf–O bond length is 2.25 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.17 Å. Both Hf–O bond lengths are 2.26 Å. In the fourteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN3O3 octahedra, edges with five HfN4O2 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Hf–N bond distances ranging from 2.08–2.16 Å. There are a spread of Hf–O bond distances ranging from 2.12–2.26 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with five HfN4O2 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.25 Å. The Hf–O bond length is 2.21 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.14–2.25 Å. The Hf–O bond length is 2.19 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2-

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of corner and edge-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Hf–N bond distances ranging from 2.08–2.12 Å. There are a spread of Hf–O bond distances ranging from 2.19–2.25 Å. In the second Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted corner and edge-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–53°. There are one shorter (2.12 Å) and two longer (2.15 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.10–2.25 Å. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with five HfN3O3 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Hf–N bond distances ranging from 2.13–2.22 Å. There are one shorter (2.14 Å) and one longer (2.20 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN4O2 octahedra, edges with five HfN3O3 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.07–2.11 Å. There are a spread of Hf–O bond distances ranging from 2.17–2.32 Å. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 pentagonal pyramids that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 48–57°. There are a spread of Hf–N bond distances ranging from 2.07–2.19 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.23 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are two shorter (2.14 Å) and two longer (2.19 Å) Hf–N bond lengths. There are one shorter (2.15 Å) and one longer (2.17 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.13–2.21 Å. There are one shorter (2.16 Å) and one longer (2.22 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted corner and edge-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Hf–N bond distances ranging from 2.10–2.21 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.19 Å. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with five HfN4O2 octahedra, a cornercorner with one HfN3O3 pentagonal pyramid, and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–59°. There are a spread of Hf–N bond distances ranging from 2.08–2.18 Å. Both Hf–O bond lengths are 2.28 Å. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted corner and edge-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–60°. There are a spread of Hf–N bond distances ranging from 2.12–2.25 Å. The Hf–O bond length is 2.25 Å. In the eleventh Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of corner and edge-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 53–60°. There are a spread of Hf–N bond distances ranging from 2.10–2.21 Å. The Hf–O bond length is 2.32 Å. In the twelfth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra, edges with five HfN4O2 octahedra, and an edgeedge with one HfN3O3 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.14–2.20 Å. There are one shorter (2.15 Å) and one longer (2.18 Å) Hf–O bond lengths. In the thirteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted corner and edge-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.20 Å. The Hf–O bond length is 2.30 Å. In the fourteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted corner and edge-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.25 Å. The Hf–O bond length is 2.21 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.08–2.17 Å. There are one shorter (2.30 Å) and one longer (2.35 Å) Hf–O bond lengths. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–55°. There are a spread of Hf–N bond distances ranging from 2.15–2.23 Å. The Hf–O bond length is 2.19 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with four NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with three NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with four NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and an edgeedge with one OHf4 trigonal pyramid. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and an edgeedge with one OHf4 trigonal pyramid. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, edges with two NHf4 tetrahedra, and edges with two NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with four NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with three NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with five NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with three NHf4 tetrahedra, and an edgeedge with one OHf4 trigonal pyramid. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, edges with two NHf4

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to two N3- and four O2- atoms to form a mixture of edge and corner-sharing HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are one shorter (2.12 Å) and one longer (2.15 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.10–2.15 Å. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.12–2.24 Å. There are one shorter (2.13 Å) and one longer (2.23 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.13–2.24 Å. There are one shorter (2.14 Å) and one longer (2.18 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.22 Å. There are one shorter (2.15 Å) and one longer (2.18 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 49–59°. There are a spread of Hf–N bond distances ranging from 2.07–2.20 Å. There are a spread of Hf–O bond distances ranging from 2.11–2.24 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.19 Å. There are one shorter (2.19 Å) and one longer (2.28 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 54–57°. There are a spread of Hf–N bond distances ranging from 2.16–2.20 Å. There are one shorter (2.15 Å) and one longer (2.17 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.21 Å. The Hf–O bond length is 2.29 Å. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Hf–N bond distances ranging from 2.13–2.22 Å. There are one shorter (2.13 Å) and one longer (2.25 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.25 Å. There are one shorter (2.24 Å) and one longer (2.27 Å) Hf–O bond lengths. In the eleventh Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 55–59°. There are a spread of Hf–N bond distances ranging from 2.11–2.22 Å. The Hf–O bond length is 2.33 Å. In the twelfth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 49–59°. There are a spread of Hf–N bond distances ranging from 2.09–2.23 Å. There are one shorter (2.22 Å) and one longer (2.28 Å) Hf–O bond lengths. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Hf–N bond distances ranging from 2.08–2.18 Å. There are one shorter (2.26 Å) and one longer (2.29 Å) Hf–O bond lengths. In the fourteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.12–2.27 Å. The Hf–O bond length is 2.23 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Hf–N bond distances ranging from 2.07–2.15 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.25 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.15–2.24 Å. The Hf–O bond length is 2.18 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 trigonal pyramid, and edges with three OHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with five OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with five O

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of Hf–N bond distances ranging from 2.10–2.20 Å. There are one shorter (2.22 Å) and one longer (2.25 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.09–2.20 Å. There are one shorter (2.20 Å) and one longer (2.31 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.19 Å. There are one shorter (2.22 Å) and one longer (2.26 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 52–54°. There are a spread of Hf–N bond distances ranging from 2.11–2.17 Å. There are a spread of Hf–O bond distances ranging from 2.15–2.19 Å. In the fifth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Hf–N bond distances ranging from 2.08–2.11 Å. There are a spread of Hf–O bond distances ranging from 2.17–2.29 Å. In the sixth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Hf–N bond distances ranging from 2.11–2.20 Å. There are one shorter (2.21 Å) and one longer (2.23 Å) Hf–O bond lengths. In the seventh Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form HfN3O3 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are one shorter (2.08 Å) and two longer (2.09 Å) Hf–N bond lengths. There are two shorter (2.23 Å) and one longer (2.25 Å) Hf–O bond lengths. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Hf–N bond distances ranging from 2.09–2.19 Å. There are one shorter (2.26 Å) and one longer (2.27 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.17 Å. There are one shorter (2.18 Å) and one longer (2.30 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Hf–N bond distances ranging from 2.11–2.20 Å. The Hf–O bond length is 2.27 Å. In the eleventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Hf–N bond distances ranging from 2.08–2.17 Å. There are one shorter (2.18 Å) and one longer (2.28 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Hf–N bond distances ranging from 2.14–2.25 Å. The Hf–O bond length is 2.22 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Hf–N bond distances ranging from 2.10–2.23 Å. There are one shorter (2.19 Å) and one longer (2.21 Å) Hf–O bond lengths. In the fourteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.21 Å. The Hf–O bond length is 2.23 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.14–2.19 Å. Both Hf–O bond lengths are 2.17 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.25 Å. There are one shorter (2.14 Å) and one longer (2.24 Å) Hf–O bond lengths. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, edges with two NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and an edgeedge with one OHf4 trigonal pyramid. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with five NHf4 trigonal pyramids, corners with seven OHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five NHf4 trigonal pyramids, corners with six OHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with five OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with four OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, corners with four OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the third O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with two NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with nine NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fifth O2- si

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N2O by Materials Project

Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Hf–N bond distances ranging from 2.09–2.18 Å. There are one shorter (2.26 Å) and one longer (2.31 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.06–2.14 Å. There are a spread of Hf–O bond distances ranging from 2.13–2.29 Å. In the third Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Hf–N bond distances ranging from 2.13–2.23 Å. There are one shorter (2.14 Å) and one longer (2.24 Å) Hf–O bond lengths. In the fourth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form distorted HfN4O2 octahedra that share corners with six HfN2O4 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 53–59°. There are a spread of Hf–N bond distances ranging from 2.14–2.27 Å. There are one shorter (2.13 Å) and one longer (2.23 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form a mixture of distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Hf–N bond distances ranging from 2.11–2.23 Å. There are one shorter (2.22 Å) and one longer (2.23 Å) Hf–O bond lengths. In the sixth Hf4+ site, Hf4+ is bonded to two N3- and four O2- atoms to form a mixture of distorted edge and corner-sharing HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are one shorter (2.07 Å) and one longer (2.09 Å) Hf–N bond lengths. There are a spread of Hf–O bond distances ranging from 2.13–2.23 Å. In the seventh Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 54–57°. There are a spread of Hf–N bond distances ranging from 2.10–2.22 Å. Both Hf–O bond lengths are 2.26 Å. In the eighth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.17 Å. There are one shorter (2.21 Å) and one longer (2.25 Å) Hf–O bond lengths. In the ninth Hf4+ site, Hf4+ is bonded to four N3- and two O2- atoms to form HfN4O2 octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Hf–N bond distances ranging from 2.10–2.24 Å. There are one shorter (2.27 Å) and one longer (2.29 Å) Hf–O bond lengths. In the tenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.10–2.22 Å. The Hf–O bond length is 2.29 Å. In the eleventh Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form a mixture of distorted edge and corner-sharing HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Hf–N bond distances ranging from 2.11–2.23 Å. There are two shorter (2.13 Å) and one longer (2.20 Å) Hf–O bond lengths. In the twelfth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Hf–N bond distances ranging from 2.13–2.25 Å. The Hf–O bond length is 2.21 Å. In the thirteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN4O2 octahedra and edges with six HfN3O3 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.27 Å. The Hf–O bond length is 2.21 Å. In the fourteenth Hf4+ site, Hf4+ is bonded to three N3- and three O2- atoms to form distorted HfN3O3 octahedra that share corners with six HfN4O2 octahedra and edges with six HfN2O4 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Hf–N bond distances ranging from 2.10–2.19 Å. There are a spread of Hf–O bond distances ranging from 2.14–2.22 Å. In the fifteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form distorted HfN5O octahedra that share corners with six HfN3O3 octahedra and edges with six HfN4O2 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Hf–N bond distances ranging from 2.13–2.24 Å. The Hf–O bond length is 2.24 Å. In the sixteenth Hf4+ site, Hf4+ is bonded to five N3- and one O2- atom to form a mixture of distorted edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–N bond distances ranging from 2.11–2.22 Å. The Hf–O bond length is 2.30 Å. There are sixteen inequivalent N3- sites. In the first N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two OHf4 tetrahedra, and edges with two OHf4 trigonal pyramids. In the third N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the seventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with two OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the eighth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the ninth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share corners with two OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the tenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with two OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the eleventh N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the twelfth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, edges with two NHf4 trigonal pyramids, and edges with two OHf4 trigonal pyramids. In the thirteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with three OHf4 trigonal pyramids, corners with nine NHf4 trigonal pyramids, an edgeedge with one OHf4 tetrahedra, an edgeedge with one OHf4 trigonal pyramid, and edges with two NHf4 trigonal pyramids. In the fourteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one OHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the fifteenth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. In the sixteenth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, an edgeedge with one OHf4 trigonal pyramid, and edges with three NHf4 trigonal pyramids. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 tetrahedra that share a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with eight NHf4 trigonal pyramids, an edgeedge with one NHf4 tetrahedra, an edgeedge with one NHf4 trigonal pyramid, and edges with two OHf4 trigonal pyramids. In the second O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share a cornercorner with one NHf4 tetrahedra, a cornercorner with one OHf4 tetrahedra, corners with three OHf4 trigonal pyramids, corners with seven NHf4 trigonal pyramids, and edges with four NHf4 trigonal pyramids. In the third O2- site,

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