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All sourcesNASA NTRSDOE OSTI
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 Hf2Cr3Si by Materials Project

Hf2Cr3Si crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Hf is bonded in a 12-coordinate geometry to nine equivalent Cr and three equivalent Si atoms. There are six shorter (2.93 Å) and three longer (2.94 Å) Hf–Cr bond lengths. All Hf–Si bond lengths are 2.93 Å. Cr is bonded to six equivalent Hf, four equivalent Cr, and two equivalent Si atoms to form CrHf6Cr4Si2 cuboctahedra that share corners with four equivalent SiHf6Cr6 cuboctahedra, corners with fourteen equivalent CrHf6Cr4Si2 cuboctahedra, edges with six equivalent CrHf6Cr4Si2 cuboctahedra, faces with six equivalent SiHf6Cr6 cuboctahedra, and faces with twelve equivalent CrHf6Cr4Si2 cuboctahedra. There are two shorter (2.41 Å) and two longer (2.58 Å) Cr–Cr bond lengths. Both Cr–Si bond lengths are 2.55 Å. Si is bonded to six equivalent Hf and six equivalent Cr atoms to form SiHf6Cr6 cuboctahedra that share corners with twelve equivalent CrHf6Cr4Si2 cuboctahedra, edges with six equivalent SiHf6Cr6 cuboctahedra, faces with two equivalent SiHf6Cr6 cuboctahedra, and faces with eighteen equivalent CrHf6Cr4Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfCrSi2 by Materials Project

HfCrSi2 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are two inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight Si4- atoms. There are a spread of Hf–Si bond distances ranging from 2.74–2.89 Å. In the second Hf4+ site, Hf4+ is bonded to seven Si4- atoms to form a mixture of edge and corner-sharing HfSi7 pentagonal bipyramids. There are a spread of Hf–Si bond distances ranging from 2.70–2.81 Å. There are two inequivalent Cr4+ sites. In the first Cr4+ site, Cr4+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Cr–Si bond distances ranging from 2.39–2.50 Å. In the second Cr4+ site, Cr4+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are four shorter (2.48 Å) and two longer (2.50 Å) Cr–Si bond lengths. There are five inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to six Hf4+, two equivalent Cr4+, and one Si4- atom. The Si–Si bond length is 2.43 Å. In the second Si4- site, Si4- is bonded in a 2-coordinate geometry to four equivalent Hf4+, two equivalent Cr4+, and one Si4- atom. The Si–Si bond length is 2.51 Å. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to five Hf4+ and four Cr4+ atoms. In the fourth Si4- site, Si4- is bonded in a 6-coordinate geometry to two equivalent Hf4+ and four Cr4+ atoms. In the fifth Si4- site, Si4- is bonded in a 7-coordinate geometry to three Hf4+, three Cr4+, and one Si4- atom. The Si–Si bond length is 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2Cr4Si5 by Materials Project

Hf2Cr4Si5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Hf4+ is bonded to seven Si4- atoms to form a mixture of corner, edge, and face-sharing HfSi7 pentagonal bipyramids. There are a spread of Hf–Si bond distances ranging from 2.62–2.79 Å. There are two inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded in a 8-coordinate geometry to two equivalent Cr3+ and six Si4- atoms. Both Cr–Cr bond lengths are 2.46 Å. There are a spread of Cr–Si bond distances ranging from 2.45–2.55 Å. In the second Cr3+ site, Cr3+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of Cr–Si bond distances ranging from 2.41–2.80 Å. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Hf4+ and five Cr3+ atoms. In the second Si4- site, Si4- is bonded in a 10-coordinate geometry to four equivalent Hf4+, four equivalent Cr3+, and two equivalent Si4- atoms. Both Si–Si bond lengths are 2.46 Å. In the third Si4- site, Si4- is bonded in a 10-coordinate geometry to one Hf4+, six Cr3+, and three equivalent Si4- atoms. There are one shorter (2.34 Å) and two longer (2.71 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗