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DOE OSTI2020

Materials Data on Mg(NiO2)2 by Materials Project

Mg(NiO2)2 is Spinel structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with twelve NiO6 octahedra. The corner-sharing octahedra tilt angles range from 55–62°. All Mg–O bond lengths are 1.99 Å. There are four inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent MgO4 tetrahedra and edges with six NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.94–2.08 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent MgO4 tetrahedra and edges with six NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.96–2.04 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent MgO4 tetrahedra and edges with six NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.94–2.04 Å. In the fourth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent MgO4 tetrahedra and edges with six NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.95–2.04 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(NiO2)4 by Materials Project

Mg(NiO2)4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Mg2+ is bonded to five O2- atoms to form MgO5 square pyramids that share corners with six NiO6 octahedra, edges with three NiO6 octahedra, edges with two equivalent MgO5 square pyramids, and a faceface with one NiO6 octahedra. The corner-sharing octahedra tilt angles range from 10–55°. There are a spread of Mg–O bond distances ranging from 2.04–2.16 Å. There are four inequivalent Ni+3.50+ sites. In the first Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, edges with four NiO6 octahedra, and edges with two equivalent MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Ni–O bond distances ranging from 1.88–1.97 Å. In the second Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with two equivalent MgO5 square pyramids, edges with four NiO6 octahedra, and a faceface with one MgO5 square pyramid. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Ni–O bond distances ranging from 1.90–2.09 Å. In the third Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with two equivalent MgO5 square pyramids, and edges with four NiO6 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Ni–O bond distances ranging from 1.85–1.93 Å. In the fourth Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with two equivalent MgO5 square pyramids, edges with four NiO6 octahedra, and an edgeedge with one MgO5 square pyramid. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Ni–O bond distances ranging from 1.87–2.05 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ni+3.50+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Ni+3.50+ atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to three Ni+3.50+ atoms. In the fourth O2- site, O2- is bonded to one Mg2+ and three Ni+3.50+ atoms to form distorted OMgNi3 trigonal pyramids that share corners with two equivalent OMgNi3 trigonal pyramids, edges with two equivalent OMg2Ni3 square pyramids, and edges with two equivalent OMg2Ni3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni+3.50+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Mg2+ and three Ni+3.50+ atoms to form distorted OMg2Ni3 trigonal bipyramids that share corners with two equivalent OMg2Ni3 square pyramids, an edgeedge with one OMg2Ni3 square pyramid, edges with two equivalent OMg2Ni3 trigonal bipyramids, and edges with two equivalent OMgNi3 trigonal pyramids. In the seventh O2- site, O2- is bonded to two equivalent Mg2+ and three Ni+3.50+ atoms to form OMg2Ni3 square pyramids that share corners with two equivalent OMg2Ni3 trigonal bipyramids, edges with two equivalent OMg2Ni3 square pyramids, an edgeedge with one OMg2Ni3 trigonal bipyramid, and edges with two equivalent OMgNi3 trigonal pyramids. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(NiO2)2 by Materials Project

Zn(NiO2)2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are four inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with two equivalent ZnO5 square pyramids, edges with four NiO6 octahedra, and edges with three ZnO5 square pyramids. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Ni–O bond distances ranging from 1.85–2.10 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with four ZnO5 square pyramids, edges with four NiO6 octahedra, and a faceface with one ZnO5 square pyramid. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Ni–O bond distances ranging from 1.91–2.22 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form distorted NiO6 octahedra that share corners with four NiO6 octahedra, corners with four ZnO5 square pyramids, edges with four NiO6 octahedra, and a faceface with one ZnO5 square pyramid. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Ni–O bond distances ranging from 1.92–2.30 Å. In the fourth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with two equivalent ZnO5 square pyramids, edges with four NiO6 octahedra, and edges with three ZnO5 square pyramids. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Ni–O bond distances ranging from 1.86–2.09 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 square pyramids that share corners with six NiO6 octahedra, edges with three NiO6 octahedra, edges with two equivalent ZnO5 square pyramids, and a faceface with one NiO6 octahedra. The corner-sharing octahedra tilt angles range from 11–58°. There are a spread of Zn–O bond distances ranging from 2.04–2.14 Å. In the second Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 square pyramids that share corners with six NiO6 octahedra, edges with three NiO6 octahedra, edges with two equivalent ZnO5 square pyramids, and a faceface with one NiO6 octahedra. The corner-sharing octahedra tilt angles range from 12–55°. There are a spread of Zn–O bond distances ranging from 2.03–2.12 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to three Ni3+ and one Zn2+ atom to form OZnNi3 trigonal pyramids that share corners with two equivalent OZn2Ni3 square pyramids, corners with two equivalent OZnNi3 trigonal pyramids, and edges with three OZn2Ni3 square pyramids. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Ni3+ atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to three Ni3+ atoms. In the fourth O2- site, O2- is bonded to three Ni3+ and one Zn2+ atom to form OZnNi3 trigonal pyramids that share corners with two equivalent OZn2Ni3 square pyramids, corners with two equivalent OZnNi3 trigonal pyramids, and edges with three OZn2Ni3 square pyramids. In the fifth O2- site, O2- is bonded to three Ni3+ and two equivalent Zn2+ atoms to form OZn2Ni3 square pyramids that share corners with two equivalent OZnNi3 trigonal pyramids, edges with four OZn2Ni3 square pyramids, and edges with three OZnNi3 trigonal pyramids. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to three Ni3+ and two equivalent Zn2+ atoms. In the seventh O2- site, O2- is bonded to three Ni3+ and two equivalent Zn2+ atoms to form OZn2Ni3 square pyramids that share corners with two equivalent OZnNi3 trigonal pyramids, edges with four OZn2Ni3 square pyramids, and edges with three OZnNi3 trigonal pyramids. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to three Ni3+ and two equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NiO2)4 by Materials Project

Ca(NiO2)4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Ca2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ca–O bond distances ranging from 2.45–2.89 Å. There are four inequivalent Ni+3.50+ sites. In the first Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Ni–O bond distances ranging from 1.84–1.99 Å. In the second Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Ni–O bond distances ranging from 1.86–2.03 Å. In the third Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 54–56°. There are a spread of Ni–O bond distances ranging from 1.84–1.99 Å. In the fourth Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 54–57°. There are a spread of Ni–O bond distances ranging from 1.85–2.01 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three Ni+3.50+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and three Ni+3.50+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and three Ni+3.50+ atoms. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to three Ni+3.50+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and three Ni+3.50+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Ca2+ and three Ni+3.50+ atoms to form distorted edge-sharing OCa2Ni3 trigonal bipyramids. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Ca2+ and three Ni+3.50+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and three Ni+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NiO2)2 by Materials Project

Ca(NiO2)2 crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with six equivalent NiO6 octahedra and edges with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 6–19°. There are two shorter (2.35 Å) and four longer (2.36 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are two shorter (2.33 Å) and four longer (2.35 Å) Ca–O bond lengths. There are two inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three equivalent CaO6 pentagonal pyramids, edges with six NiO6 octahedra, and an edgeedge with one CaO6 pentagonal pyramid. There are a spread of Ni–O bond distances ranging from 1.92–2.06 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share edges with six NiO6 octahedra and edges with two equivalent CaO6 pentagonal pyramids. There are a spread of Ni–O bond distances ranging from 1.94–2.08 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four equivalent OCa2Ni3 trigonal bipyramids, corners with six OCaNi3 trigonal pyramids, edges with four equivalent OCa2Ni3 trigonal bipyramids, and an edgeedge with one OCaNi3 trigonal pyramid. In the second O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four equivalent OCa2Ni3 trigonal bipyramids, corners with six OCaNi3 trigonal pyramids, edges with four equivalent OCa2Ni3 trigonal bipyramids, and an edgeedge with one OCaNi3 trigonal pyramid. In the third O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form OCa2Ni3 trigonal bipyramids that share corners with five equivalent OCa2Ni3 trigonal bipyramids, corners with four OCaNi3 trigonal pyramids, edges with four equivalent OCa2Ni3 trigonal bipyramids, and edges with four OCaNi3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(NiO2)2 by Materials Project

Mg(NiO2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.19–2.41 Å. There are two inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–63°. There is four shorter (1.92 Å) and two longer (2.00 Å) Ni–O bond length. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–63°. There are a spread of Ni–O bond distances ranging from 1.91–2.05 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Mg2+ and three equivalent Ni3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids. In the second O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Ni3+ atoms. In the third O2- site, O2- is bonded to two equivalent Mg2+ and three equivalent Ni3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 square pyramids. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Ni3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(NiO2)2 by Materials Project

Mg(NiO2)2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 square pyramids that share corners with four NiO6 octahedra, corners with four NiO5 square pyramids, an edgeedge with one NiO5 square pyramid, edges with two equivalent MgO5 square pyramids, and a faceface with one NiO6 octahedra. The corner-sharing octahedra tilt angles range from 39–59°. There are a spread of Mg–O bond distances ranging from 1.99–2.11 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 square pyramids that share corners with four NiO6 octahedra, corners with four NiO5 square pyramids, an edgeedge with one NiO5 square pyramid, edges with two equivalent MgO5 square pyramids, and a faceface with one NiO6 octahedra. The corner-sharing octahedra tilt angles range from 39–59°. There are a spread of Mg–O bond distances ranging from 1.99–2.11 Å. There are four inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to five O2- atoms to form NiO5 square pyramids that share corners with four NiO6 octahedra, corners with four MgO5 square pyramids, an edgeedge with one MgO5 square pyramid, and edges with two equivalent NiO5 square pyramids. The corner-sharing octahedra tilt angles range from 49–54°. There are a spread of Ni–O bond distances ranging from 1.92–2.00 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four MgO5 square pyramids, corners with four NiO5 square pyramids, edges with four NiO6 octahedra, and a faceface with one MgO5 square pyramid. There are a spread of Ni–O bond distances ranging from 1.88–2.05 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four MgO5 square pyramids, corners with four NiO5 square pyramids, edges with four NiO6 octahedra, and a faceface with one MgO5 square pyramid. There are a spread of Ni–O bond distances ranging from 1.89–2.04 Å. In the fourth Ni3+ site, Ni3+ is bonded to five O2- atoms to form NiO5 square pyramids that share corners with four NiO6 octahedra, corners with four MgO5 square pyramids, an edgeedge with one MgO5 square pyramid, and edges with two equivalent NiO5 square pyramids. The corner-sharing octahedra tilt angles range from 49–54°. There are a spread of Ni–O bond distances ranging from 1.92–2.00 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mg2+ and three Ni3+ atoms to form distorted OMgNi3 trigonal pyramids that share a cornercorner with one OMg2Ni3 trigonal bipyramid, corners with two equivalent OMgNi3 trigonal pyramids, and edges with two equivalent OMg2Ni3 trigonal bipyramids. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Ni3+ atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to three Ni3+ atoms. In the fourth O2- site, O2- is bonded to one Mg2+ and three Ni3+ atoms to form distorted OMgNi3 trigonal pyramids that share a cornercorner with one OMg2Ni3 trigonal bipyramid, corners with two equivalent OMgNi3 trigonal pyramids, and edges with two equivalent OMg2Ni3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a square co-planar geometry to two equivalent Mg2+ and two equivalent Ni3+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Mg2+ and three Ni3+ atoms to form distorted OMg2Ni3 trigonal bipyramids that share a cornercorner with one OMgNi3 trigonal pyramid, edges with four OMg2Ni3 trigonal bipyramids, and edges with two equivalent OMgNi3 trigonal pyramids. In the seventh O2- site, O2- is bonded in a square co-planar geometry to two equivalent Mg2+ and two equivalent Ni3+ atoms. In the eighth O2- site, O2- is bonded to two equivalent Mg2+ and three Ni3+ atoms to form distorted OMg2Ni3 trigonal bipyramids that share a cornercorner with one OMgNi3 trigonal pyramid, edges with four OMg2Ni3 trigonal bipyramids, and edges with two equivalent OMgNi3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NiO2)2 by Materials Project

Ca(NiO2)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.41 Å. In the second Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.40 Å. There are four inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to five O2- atoms to form NiO5 square pyramids that share corners with four NiO6 octahedra and edges with two equivalent NiO5 square pyramids. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Ni–O bond distances ranging from 1.94–2.02 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO5 square pyramids and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.90–2.03 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO5 square pyramids and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.91–2.05 Å. In the fourth Ni3+ site, Ni3+ is bonded to five O2- atoms to form NiO5 square pyramids that share corners with four NiO6 octahedra and edges with two equivalent NiO5 square pyramids. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Ni–O bond distances ranging from 1.93–2.04 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ni3+ atoms. In the second O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 tetrahedra that share corners with two equivalent OCa2Ni3 square pyramids, corners with two equivalent OCaNi3 tetrahedra, and edges with three OCa2Ni3 square pyramids. In the third O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with two equivalent OCa2Ni3 square pyramids, corners with two equivalent OCaNi3 trigonal pyramids, and edges with three OCa2Ni3 square pyramids. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ni3+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Ca2+ and two equivalent Ni3+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Ca2+ and three Ni3+ atoms to form distorted OCa2Ni3 square pyramids that share corners with two equivalent OCaNi3 trigonal pyramids, edges with four OCa2Ni3 square pyramids, edges with two equivalent OCaNi3 tetrahedra, and an edgeedge with one OCaNi3 trigonal pyramid. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Ca2+ and two equivalent Ni3+ atoms. In the eighth O2- site, O2- is bonded to two equivalent Ca2+ and three Ni3+ atoms to form distorted OCa2Ni3 square pyramids that share corners with two equivalent OCaNi3 tetrahedra, edges with four OCa2Ni3 square pyramids, an edgeedge with one OCaNi3 tetrahedra, and edges with two equivalent OCaNi3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NiO2)2 by Materials Project

Ca(NiO2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.37–2.48 Å. There are two inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–58°. There are a spread of Ni–O bond distances ranging from 1.97–2.02 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–58°. There are a spread of Ni–O bond distances ranging from 1.99–2.06 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ca2+ and three equivalent Ni3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Ni3 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent Ca2+ and three Ni3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Ni3 trigonal bipyramids. In the third O2- site, O2- is bonded to two equivalent Ca2+ and three equivalent Ni3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Ni3 square pyramids. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Ca2+ and three Ni3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(NiO2)2 by Materials Project

Zn(NiO2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Ni–O bond distances ranging from 1.91–2.01 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Ni–O bond distances ranging from 1.94–2.05 Å. Zn2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Zn–O bond distances ranging from 2.19–2.44 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Ni3+ and two equivalent Zn2+ atoms to form a mixture of distorted corner and edge-sharing OZn2Ni3 trigonal bipyramids. In the second O2- site, O2- is bonded in a 5-coordinate geometry to three Ni3+ and two equivalent Zn2+ atoms. In the third O2- site, O2- is bonded to three equivalent Ni3+ and two equivalent Zn2+ atoms to form a mixture of distorted corner and edge-sharing OZn2Ni3 square pyramids. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to three Ni3+ and two equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiO2 by Materials Project

NiO2 crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are two inequivalent Ni4+ sites. In the first Ni4+ site, Ni4+ is bonded to four O2- atoms to form corner-sharing NiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–58°. There is three shorter (1.85 Å) and one longer (1.90 Å) Ni–O bond length. In the second Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three equivalent NiO4 tetrahedra and edges with four equivalent NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.85–1.99 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ni4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to four Ni4+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three equivalent Ni4+ atoms. In the fourth O2- site, O2- is bonded in a water-like geometry to two equivalent Ni4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NiO2)2 by Materials Project

Ca(NiO2)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with six NiO6 octahedra and edges with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–20°. There are a spread of Ca–O bond distances ranging from 2.36–2.39 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with six NiO6 octahedra and edges with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–20°. There are a spread of Ca–O bond distances ranging from 2.35–2.39 Å. In the third Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.38 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.38 Å. There are eight inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three CaO6 pentagonal pyramids, edges with six NiO6 octahedra, and an edgeedge with one CaO6 pentagonal pyramid. There are a spread of Ni–O bond distances ranging from 1.88–2.13 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three CaO6 pentagonal pyramids, edges with six NiO6 octahedra, and an edgeedge with one CaO6 pentagonal pyramid. There are a spread of Ni–O bond distances ranging from 1.88–2.11 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three CaO6 pentagonal pyramids, edges with six NiO6 octahedra, and an edgeedge with one CaO6 pentagonal pyramid. There are a spread of Ni–O bond distances ranging from 1.88–2.13 Å. In the fourth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three CaO6 pentagonal pyramids, edges with six NiO6 octahedra, and an edgeedge with one CaO6 pentagonal pyramid. There are a spread of Ni–O bond distances ranging from 1.88–2.12 Å. In the fifth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share edges with six NiO6 octahedra and edges with two CaO6 pentagonal pyramids. There are a spread of Ni–O bond distances ranging from 1.90–2.16 Å. In the sixth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share edges with six NiO6 octahedra and edges with two CaO6 pentagonal pyramids. There are a spread of Ni–O bond distances ranging from 1.91–2.16 Å. In the seventh Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share edges with six NiO6 octahedra and edges with two CaO6 pentagonal pyramids. There are a spread of Ni–O bond distances ranging from 1.91–2.13 Å. In the eighth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share edges with six NiO6 octahedra and edges with two CaO6 pentagonal pyramids. There are a spread of Ni–O bond distances ranging from 1.91–2.14 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the second O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four OCa2Ni3 trigonal bipyramids, corners with five OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and an edgeedge with one OCaNi3 trigonal pyramid. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the fourth O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four OCa2Ni3 trigonal bipyramids, corners with five OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and an edgeedge with one OCaNi3 trigonal pyramid. In the fifth O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, and edges with four OCa2Ni3 trigonal bipyramids. In the sixth O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four OCa2Ni3 trigonal bipyramids, corners with six OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and an edgeedge with one OCaNi3 trigonal pyramid. In the seventh O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, and edges with four OCa2Ni3 trigonal bipyramids. In the eighth O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four OCa2Ni3 trigonal bipyramids, corners with six OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and an edgeedge with one OCaNi3 trigonal pyramid. In the ninth O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form distorted OCa2Ni3 trigonal bipyramids that share corners with five OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and edges with two OCaNi3 trigonal pyramids. In the tenth O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form distorted OCa2Ni3 trigonal bipyramids that share corners with five OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and edges with four OCaNi3 trigonal pyramids. In the eleventh O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form OCa2Ni3 trigonal bipyramids that share corners with five OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and edges with two OCaNi3 trigonal pyramids. In the twelfth O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form OCa2Ni3 trigonal bipyramids that share corners with five OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and edges with four OCaNi3 trigonal pyramids. In the thirteenth O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form distorted OCa2Ni3 trigonal bipyramids that share corners with five OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and edges with two OCaNi3 trigonal pyramids. In the fourteenth O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form distorted OCa2Ni3 trigonal bipyramids that share corners with five OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and edges with four OCaNi3 trigonal pyramids. In the fifteenth O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form OCa2Ni3 trigonal bipyramids that share corners with five OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and edges with two OCaNi3 trigonal pyramids. In the sixteenth O2- site, O2- is bonded to two Ca2+ and three Ni3+ atoms to form OCa2Ni3 trigonal bipyramids that share corners with five OCa2Ni3 trigonal bipyramids, corners with three OCaNi3 trigonal pyramids, edges with four OCa2Ni3 trigonal bipyramids, and edges with four OCaNi3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(NiO2)2 by Materials Project

Y(NiO2)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Y3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.35–2.41 Å. There are two inequivalent Ni+2.50+ sites. In the first Ni+2.50+ site, Ni+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.86 Å) and two longer (1.88 Å) Ni–O bond length. In the second Ni+2.50+ site, Ni+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.86 Å) and two longer (1.89 Å) Ni–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Y3+ and two Ni+2.50+ atoms to form a mixture of distorted edge and corner-sharing OY2Ni2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Y3+ and two Ni+2.50+ atoms to form a mixture of distorted edge and corner-sharing OY2Ni2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(NiO2)2 by Materials Project

Mg(NiO2)2 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with three MgO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 54–63°. There are a spread of Mg–O bond distances ranging from 1.96–2.00 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three MgO4 tetrahedra, corners with three NiO4 tetrahedra, and edges with six NiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.03–2.06 Å. In the third Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with three MgO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–62°. There are a spread of Mg–O bond distances ranging from 1.96–2.00 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO4 tetrahedra, corners with four NiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five NiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.06 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six NiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four equivalent NiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.03–2.07 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six NiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.04–2.08 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share a cornercorner with one MgO4 tetrahedra, corners with five NiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five NiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.07 Å. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six NiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.07 Å. There are twelve inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three MgO4 tetrahedra, corners with three NiO4 tetrahedra, edges with two equivalent MgO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.90–2.06 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three equivalent MgO4 tetrahedra, corners with three equivalent NiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.91–2.06 Å. In the third Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six MgO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There is two shorter (1.88 Å) and two longer (1.90 Å) Ni–O bond length. In the fourth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent MgO4 tetrahedra, corners with four NiO4 tetrahedra, edges with three MgO6 octahedra, and edges with three NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.87–2.02 Å. In the fifth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three MgO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 55–61°. There are a spread of Ni–O bond distances ranging from 1.89–1.94 Å. In the sixth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six MgO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 53–59°. There are a spread of Ni–O bond distances ranging from 1.83–1.88 Å. In the seventh Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six NiO4 tetrahedra, edges with two equivalent NiO6 octahedra, and edges with four MgO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.87–2.02 Å. In the eighth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six MgO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 54–62°. There is three shorter (1.91 Å) and one longer (1.93 Å) Ni–O bond length. In the ninth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share a cornercorner with one MgO4 tetrahedra, corners with five NiO4 tetrahedra, edges with three MgO6 octahedra, and edges with three NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.91–2.10 Å. In the tenth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six MgO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of Ni–O bond distances ranging from 1.90–2.02 Å. In the eleventh Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three equivalent MgO4 tetrahedra, corners with three equivalent NiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.87–1.91 Å. In the twelfth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three MgO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There is two shorter (1.96 Å) and two longer (1.98 Å) Ni–O bond length. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded to two Mg2+ and two Ni3+ atoms to form distorted OMg2Ni2 trigonal pyramids that share a cornercorner with one OMg2Ni2 tetrahedra, corners with five OMgNi3 trigonal pyramids, and an edgeedge with one OMg2Ni2 trigonal pyramid. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mg2+ and two equivalent Ni3+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Ni3+ atoms. In the fifth O2- site, O2- is bonded to two Mg2+ and two Ni3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Ni2 trigonal pyramids. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the eighth O2- site, O2- is bonded to one Mg2+ and three Ni3+ atoms to form distorted corner-sharing OMgNi3 trigonal pyramids. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Ni3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Ni3+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Ni3+ atoms. In the eighteenth O2- site, O2- is bonded to two Mg2+ and two Ni3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Ni2 trigonal pyramids. In the nineteenth O2- site, O2- is bonded to two Mg2+ and two equivalent Ni3+ atoms to form distorted corner-sharing OMg2Ni2 tetrahedra. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Ni3+ atoms. In the twenty-third O2- site, O2- is bonded to one Mg2+ and three Ni3+ atoms to form distorted OMgNi3 trigonal pyramids that share corners with two equivalent OMg2Ni2 tetrahedra, corners with four OMgNi3 trigonal pyramids, and an edgeedge with one OMgNi3 trigonal pyramid. In the twenty-fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ni3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiO2 by Materials Project

NiO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent Ni4+ sites. In the first Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share a cornercorner with one NiO4 tetrahedra and edges with five NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.84–1.92 Å. In the second Ni4+ site, Ni4+ is bonded to six O2- atoms to form edge-sharing NiO6 octahedra. All Ni–O bond lengths are 1.88 Å. In the third Ni4+ site, Ni4+ is bonded to six O2- atoms to form edge-sharing NiO6 octahedra. There is five shorter (1.88 Å) and one longer (1.89 Å) Ni–O bond length. In the fourth Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share a cornercorner with one NiO4 tetrahedra and edges with five NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.84–1.92 Å. In the fifth Ni4+ site, Ni4+ is bonded to six O2- atoms to form edge-sharing NiO6 octahedra. All Ni–O bond lengths are 1.88 Å. In the sixth Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share a cornercorner with one NiO4 tetrahedra and edges with five NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.84–1.92 Å. In the seventh Ni4+ site, Ni4+ is bonded to six O2- atoms to form edge-sharing NiO6 octahedra. All Ni–O bond lengths are 1.88 Å. In the eighth Ni4+ site, Ni4+ is bonded to six O2- atoms to form edge-sharing NiO6 octahedra. All Ni–O bond lengths are 1.88 Å. In the ninth Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent NiO4 tetrahedra and edges with five NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.86–1.89 Å. In the tenth Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent NiO4 tetrahedra and edges with five NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.86–1.89 Å. In the eleventh Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent NiO4 tetrahedra and edges with five NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.86–1.89 Å. In the twelfth Ni4+ site, Ni4+ is bonded to four O2- atoms to form corner-sharing NiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–59°. There is three shorter (1.87 Å) and one longer (2.01 Å) Ni–O bond length. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to two Ni4+ atoms. In the second O2- site, O2- is bonded in a water-like geometry to two Ni4+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three Ni4+ atoms. In the fourth O2- site, O2- is bonded in a water-like geometry to two Ni4+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to four Ni4+ atoms. In the eighth O2- site, O2- is bonded in a distorted T-shaped geometry to three Ni4+ atoms. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the twelfth O2- site, O2- is bonded in a distorted T-shaped geometry to three Ni4+ atoms. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the sixteenth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the twentieth O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the twenty-first O2- site, O2- is bonded in a trigonal planar geometry to three Ni4+ atoms. In the twenty-second O2- site, O2- is bonded in a trigonal planar geometry to three Ni4+ atoms. In the twenty-third O2- site, O2- is bonded in a 3-coordinate geometry to three Ni4+ atoms. In the twenty-fourth O2- site, O2- is bonded in a trigonal planar geometry to three Ni4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(NiO2)2 by Materials Project

Zn(NiO2)2 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are nine inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent ZnO4 tetrahedra, corners with four NiO4 tetrahedra, edges with three NiO6 octahedra, and edges with three ZnO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.91–2.02 Å. In the second Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six NiO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 55–62°. There are a spread of Ni–O bond distances ranging from 1.93–1.97 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three equivalent NiO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.93–2.03 Å. In the fourth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six NiO4 tetrahedra, edges with two equivalent NiO6 octahedra, and edges with four ZnO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.92–2.02 Å. In the fifth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six NiO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–59°. There are a spread of Ni–O bond distances ranging from 1.86–1.90 Å. In the sixth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share a cornercorner with one ZnO4 tetrahedra, corners with five NiO4 tetrahedra, edges with three NiO6 octahedra, and edges with three ZnO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.93–2.06 Å. In the seventh Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six NiO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Ni–O bond distances ranging from 1.89–1.91 Å. In the eighth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six NiO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 55–63°. There are a spread of Ni–O bond distances ranging from 1.93–1.98 Å. In the ninth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–63°. There is three shorter (1.95 Å) and one longer (1.97 Å) Ni–O bond length. There are six inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–62°. There is two shorter (1.97 Å) and two longer (1.98 Å) Zn–O bond length. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six NiO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.04–2.12 Å. In the third Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with two equivalent ZnO4 tetrahedra, corners with four NiO4 tetrahedra, an edgeedge with one ZnO6 octahedra, and edges with five NiO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.05–2.10 Å. In the fourth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six NiO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.04–2.12 Å. In the fifth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six NiO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four equivalent NiO6 octahedra. There are four shorter (2.03 Å) and two longer (2.11 Å) Zn–O bond lengths. In the sixth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share a cornercorner with one ZnO4 tetrahedra, corners with five NiO4 tetrahedra, an edgeedge with one ZnO6 octahedra, and edges with five NiO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.05–2.08 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ni3+ and two Zn2+ atoms to form a mixture of distorted edge and corner-sharing OZn2Ni2 trigonal pyramids. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ni3+ and two Zn2+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ni3+ and two Zn2+ atoms. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ni3+ and two Zn2+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ni3+ and two Zn2+ atoms. In the thirteenth O2- site, O2- is bonded to two equivalent Ni3+ and two Zn2+ atoms to form distorted corner-sharing OZn2Ni2 trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the sixteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Ni3+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ni3+ and one Zn2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NiO2)2 by Materials Project

Ca(NiO2)2 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are eight inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 52–75°. There are a spread of Ca–O bond distances ranging from 2.15–2.26 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with three CaO4 tetrahedra, corners with three NiO4 tetrahedra, and edges with six NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.27 Å. In the third Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 54–72°. There are a spread of Ca–O bond distances ranging from 2.14–2.26 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four NiO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.22–2.30 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four equivalent NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.23–2.29 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.33 Å. In the seventh Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five NiO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.25–2.27 Å. In the eighth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.31 Å. There are twelve inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three CaO4 tetrahedra, corners with three NiO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.88–2.24 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.87–2.18 Å. In the third Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–61°. There are a spread of Ni–O bond distances ranging from 1.87–1.90 Å. In the fourth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four NiO4 tetrahedra, edges with three CaO6 octahedra, and edges with three NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.87–2.15 Å. In the fifth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 52–65°. There are a spread of Ni–O bond distances ranging from 1.90–2.01 Å. In the sixth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 48–65°. There are a spread of Ni–O bond distances ranging from 1.84–1.92 Å. In the seventh Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six NiO4 tetrahedra, edges with two equivalent NiO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.92–2.19 Å. In the eighth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 51–68°. There are a spread of Ni–O bond distances ranging from 1.90–2.09 Å. In the ninth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five NiO4 tetrahedra, edges with three CaO6 octahedra, and edges with three NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.90–2.31 Å. In the tenth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 50–69°. There are a spread of Ni–O bond distances ranging from 1.89–2.08 Å. In the eleventh Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.85–1.94 Å. In the twelfth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 46–68°. There are a spread of Ni–O bond distances ranging from 1.99–2.21 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Ni3+ atoms to form distorted OCa2Ni2 tetrahedra that share corners with two OCa2Ni2 tetrahedra, corners with five OCaNi3 trigonal pyramids, an edgeedge with one OCa2Ni2 tetrahedra, and an edgeedge with one OCa2Ni2 trigonal pyramid. In the second O2- site, O2- is bonded to two Ca2+ and two equivalent Ni3+ atoms to form distorted OCa2Ni2 trigonal pyramids that share corners with two equivalent OCa2Ni2 tetrahedra, corners with eight OCaNi3 trigonal pyramids, and edges with two equivalent OCa2Ni2 tetrahedra. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Ni3+ atoms. In the fifth O2- site, O2- is bonded to two Ca2+ and two Ni3+ atoms to form distorted OCa2Ni2 tetrahedra that share a cornercorner with one OCa2Ni2 tetrahedra, corners with five OCa2Ni2 trigonal pyramids, an edgeedge with one OCa2Ni2 tetrahedra, and an edgeedge with one OCaNi3 trigonal pyramid. In the sixth O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with five OCa2Ni2 tetrahedra, corners with four OCa2Ni2 trigonal pyramids, and edges with two OCaNi3 trigonal pyramids. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the eighth O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four equivalent OCa2Ni2 tetrahedra, corners with three equivalent OCa2Ni2 trigonal pyramids, and edges with two equivalent OCaNi3 trigonal pyramids. In the ninth O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form a mixture of distorted edge and corner-sharing OCaNi3 trigonal pyramids. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Ni3+ atoms. In the eleventh O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with two equivalent OCa2Ni2 tetrahedra and corners with two equivalent OCaNi3 trigonal pyramids. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Ni3+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Ni3+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Ni3+ atoms. In the nineteenth O2- site, O2- is bonded to two Ca2+ and two equivalent Ni3+ atoms to form distorted corner-sharing OCa2Ni2 tetrahedra. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Ni3+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the twenty-fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NiO2)2 by Materials Project

Ca(NiO2)2 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 55–75°. There are a spread of Ca–O bond distances ranging from 2.16–2.31 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.26–2.33 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four NiO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.22–2.28 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.31 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four equivalent NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.30 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five NiO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five NiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.25–2.27 Å. There are nine inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four NiO4 tetrahedra, edges with three CaO6 octahedra, and edges with three NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.86–2.17 Å. In the second Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–61°. There are a spread of Ni–O bond distances ranging from 1.87–1.96 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent NiO4 tetrahedra, edges with two CaO6 octahedra, and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.86–1.94 Å. In the fourth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six NiO4 tetrahedra, edges with two equivalent NiO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.91–2.16 Å. In the fifth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Ni–O bond distances ranging from 1.85–1.92 Å. In the sixth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five NiO4 tetrahedra, edges with three CaO6 octahedra, and edges with three NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.92–2.32 Å. In the seventh Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 50–67°. There are a spread of Ni–O bond distances ranging from 1.91–2.07 Å. In the eighth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with six CaO6 octahedra and corners with six NiO6 octahedra. The corner-sharing octahedra tilt angles range from 51–69°. There are a spread of Ni–O bond distances ranging from 1.91–2.09 Å. In the ninth Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine NiO6 octahedra. The corner-sharing octahedra tilt angles range from 45–66°. There are a spread of Ni–O bond distances ranging from 1.95–2.19 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Ni3+ atoms to form distorted OCa2Ni2 tetrahedra that share corners with two OCa2Ni2 tetrahedra, corners with three OCaNi3 trigonal pyramids, an edgeedge with one OCa2Ni2 tetrahedra, and an edgeedge with one OCaNi3 trigonal pyramid. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the third O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with three OCa2Ni2 tetrahedra, corners with two equivalent OCaNi3 trigonal pyramids, and edges with two equivalent OCa2Ni2 tetrahedra. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Ni3+ atoms. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Ni3+ atoms. In the eighth O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with four equivalent OCa2Ni2 tetrahedra and corners with two equivalent OCaNi3 trigonal pyramids. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Ni3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Ni3+ atoms. In the thirteenth O2- site, O2- is bonded to two Ca2+ and two equivalent Ni3+ atoms to form distorted OCa2Ni2 tetrahedra that share corners with two equivalent OCa2Ni2 tetrahedra and a cornercorner with one OCaNi3 trigonal pyramid. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Ni3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Ni3+ atoms.

36 MATERIALS SCIENCE↗