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DOE OSTI2020

Materials Data on Ca(NiO2)4 by Materials Project

Ca(NiO2)4 is beta indium sulfide-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ca2+ is bonded in a distorted hexagonal planar geometry to six equivalent O2- atoms. All Ca–O bond lengths are 2.36 Å. There are two inequivalent Ni+3.50+ sites. In the first Ni+3.50+ site, Ni+3.50+ is bonded to six O2- atoms to form edge-sharing NiO6 octahedra. There is four shorter (1.89 Å) and two longer (1.91 Å) Ni–O bond length. In the second Ni+3.50+ site, Ni+3.50+ is bonded to six equivalent O2- atoms to form edge-sharing NiO6 octahedra. All Ni–O bond lengths are 2.03 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Ni+3.50+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three equivalent Ni+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(NiO2)2 by Materials Project

NiOCaONiO2 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of two nickel dihydroxide molecules and one NiOCaO sheet oriented in the (0, 1, -1) direction. In the NiOCaO sheet, Ca2+ is bonded in a 1-coordinate geometry to three O2- atoms. There are a spread of Ca–O bond distances ranging from 1.40–2.43 Å. There are two inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded in a linear geometry to two equivalent O2- atoms. Both Ni–O bond lengths are 1.41 Å. In the second Ni3+ site, Ni3+ is bonded in a distorted linear geometry to two equivalent O2- atoms. Both Ni–O bond lengths are 1.34 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+ and one Ni3+ atom. In the second O2- site, O2- is bonded in a distorted L-shaped geometry to one Ca2+ and one Ni3+ atom.

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 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 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 Ca2Ni3O8 by Materials Project

Ca2Ni3O8 is Pyrite-derived structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with seven NiO6 octahedra, edges with three NiO6 octahedra, and edges with two equivalent CaO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 21–56°. There are a spread of Ca–O bond distances ranging from 2.25–2.42 Å. There are two inequivalent Ni4+ sites. In the first Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent CaO6 pentagonal pyramids, edges with four equivalent NiO6 octahedra, and edges with two equivalent CaO6 pentagonal pyramids. There is four shorter (1.88 Å) and two 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 four equivalent CaO6 pentagonal pyramids, edges with four NiO6 octahedra, and edges with two equivalent CaO6 pentagonal pyramids. There are a spread of Ni–O bond distances ranging from 1.86–1.95 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two equivalent Ni4+ atoms. In the second O2- site, O2- is bonded to one Ca2+ and three Ni4+ atoms to form a mixture of distorted edge and corner-sharing OCaNi3 trigonal pyramids. In the third O2- site, O2- is bonded to two equivalent Ca2+ and two Ni4+ atoms to form a mixture of distorted edge and corner-sharing OCa2Ni2 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca3Ni2O7 by Materials Project

Ca3Ni2O7 is Orthorhombic Perovskite-like structured and crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.63 Å. In the second 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 2.28–2.48 Å. Ni4+ is bonded to six O2- atoms to form corner-sharing NiO6 octahedra. The corner-sharing octahedra tilt angles range from 24–25°. There are a spread of Ni–O bond distances ranging from 1.92–1.95 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent Ca2+ and one Ni4+ atom. In the second O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two equivalent Ni4+ atoms. In the third O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two equivalent Ni4+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+ and two equivalent Ni4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca2Ni2O5 by Materials Project

Ca2Ni2O5 crystallizes in the orthorhombic Pbam 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 2.40–2.90 Å. Ni3+ is bonded to five O2- atoms to form corner-sharing NiO5 square pyramids. There are a spread of Ni–O bond distances ranging from 1.87–1.96 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Ca2+ and two equivalent Ni3+ atoms to form distorted edge-sharing OCa4Ni2 octahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to four equivalent Ca2+ and two equivalent Ni3+ atoms. In the third O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent Ca2+ and two equivalent Ni3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaNi2O5 by Materials Project

CaNi2O5 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.27–2.51 Å. In the second Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.53 Å. There are four inequivalent Ni4+ sites. In the first Ni4+ site, Ni4+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing NiO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 1.84–2.02 Å. In the second Ni4+ site, Ni4+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing NiO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 1.84–2.02 Å. In the third Ni4+ site, Ni4+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing NiO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 1.83–2.01 Å. In the fourth Ni4+ site, Ni4+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing NiO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 1.83–2.01 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ca2+ and two Ni4+ atoms to form corner-sharing OCa2Ni2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Ca2+ and two Ni4+ atoms to form corner-sharing OCa2Ni2 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Ni4+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Ni4+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Ni4+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Ni4+ atoms. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+, one Ni4+, and one O2- atom. The O–O bond length is 1.45 Å. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+, one Ni4+, and one O2- atom. The O–O bond length is 1.46 Å. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+, one Ni4+, and one O2- atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+, one Ni4+, and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaNiO2 by Materials Project

NiOCaO 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 octahedra that share corners with two equivalent CaO6 octahedra, corners with two NiO4 trigonal pyramids, edges with seven CaO6 octahedra, and an edgeedge with one NiO4 trigonal pyramid. The corner-sharing octahedral tilt angles are 1°. There are a spread of Ca–O bond distances ranging from 2.29–2.85 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with two NiO4 trigonal pyramids, edges with seven CaO6 octahedra, and an edgeedge with one NiO4 trigonal pyramid. The corner-sharing octahedral tilt angles are 1°. There are a spread of Ca–O bond distances ranging from 2.29–2.85 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with two equivalent NiO4 trigonal pyramids, edges with seven CaO6 octahedra, and edges with three NiO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 1°. There are a spread of Ca–O bond distances ranging from 2.29–2.42 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with two equivalent NiO4 trigonal pyramids, edges with seven CaO6 octahedra, and edges with three NiO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 1°. There are a spread of Ca–O bond distances ranging from 2.29–2.42 Å. There are four inequivalent Ni2+ sites. In the first Ni2+ site, Ni2+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are a spread of Ni–O bond distances ranging from 1.93–2.23 Å. In the second Ni2+ site, Ni2+ is bonded to four O2- atoms to form distorted NiO4 trigonal pyramids that share corners with four CaO6 octahedra, corners with two equivalent NiO4 trigonal pyramids, and edges with four CaO6 octahedra. The corner-sharing octahedra tilt angles range from 8–85°. There are a spread of Ni–O bond distances ranging from 1.98–2.11 Å. In the third Ni2+ site, Ni2+ is bonded to four O2- atoms to form distorted NiO4 trigonal pyramids that share corners with four CaO6 octahedra, corners with two equivalent NiO4 trigonal pyramids, and edges with four CaO6 octahedra. The corner-sharing octahedra tilt angles range from 8–85°. There are a spread of Ni–O bond distances ranging from 1.98–2.10 Å. In the fourth Ni2+ site, Ni2+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are a spread of Ni–O bond distances ranging from 1.93–2.25 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ca2+ and three Ni2+ atoms to form distorted OCaNi3 tetrahedra that share corners with two OCa5Ni octahedra, corners with six OCa3Ni2 square pyramids, corners with two equivalent OCaNi3 tetrahedra, an edgeedge with one OCa5Ni octahedra, and an edgeedge with one OCa3Ni2 square pyramid. The corner-sharing octahedra tilt angles range from 11–85°. In the second O2- site, O2- is bonded to three Ca2+ and two equivalent Ni2+ atoms to form OCa3Ni2 square pyramids that share corners with two equivalent OCa5Ni octahedra, corners with three OCa3Ni2 square pyramids, corners with two equivalent OCaNi3 tetrahedra, edges with three OCa5Ni octahedra, and edges with four OCa3Ni2 square pyramids. The corner-sharing octahedral tilt angles are 9°. In the third O2- site, O2- is bonded to three Ca2+ and two equivalent Ni2+ atoms to form OCa3Ni2 square pyramids that share corners with two equivalent OCa5Ni octahedra, corners with three OCa3Ni2 square pyramids, corners with two equivalent OCaNi3 tetrahedra, edges with three OCa5Ni octahedra, and edges with four OCa3Ni2 square pyramids. The corner-sharing octahedral tilt angles are 9°. In the fourth O2- site, O2- is bonded to one Ca2+ and three Ni2+ atoms to form distorted OCaNi3 tetrahedra that share corners with two OCa5Ni octahedra, corners with six OCa3Ni2 square pyramids, corners with two equivalent OCaNi3 tetrahedra, an edgeedge with one OCa5Ni octahedra, and an edgeedge with one OCa3Ni2 square pyramid. The corner-sharing octahedra tilt angles range from 11–85°. In the fifth O2- site, O2- is bonded to three Ca2+ and two equivalent Ni2+ atoms to form distorted OCa3Ni2 square pyramids that share corners with two equivalent OCa5Ni octahedra, corners with three OCa3Ni2 square pyramids, corners with four OCaNi3 tetrahedra, edges with three OCa5Ni octahedra, edges with two equivalent OCa3Ni2 square pyramids, and an edgeedge with one OCaNi3 tetrahedra. The corner-sharing octahedral tilt angles are 13°. In the sixth O2- site, O2- is bonded to five Ca2+ and one Ni2+ atom to form distorted OCa5Ni octahedra that share corners with four OCa3Ni2 square pyramids, corners with two OCaNi3 tetrahedra, edges with four OCa5Ni octahedra, edges with six OCa3Ni2 square pyramids, and an edgeedge with one OCaNi3 tetrahedra. In the seventh O2- site, O2- is bonded to three Ca2+ and two equivalent Ni2+ atoms to form distorted OCa3Ni2 square pyramids that share corners with two equivalent OCa5Ni octahedra, corners with three OCa3Ni2 square pyramids, corners with four OCaNi3 tetrahedra, edges with three OCa5Ni octahedra, edges with two equivalent OCa3Ni2 square pyramids, and an edgeedge with one OCaNi3 tetrahedra. The corner-sharing octahedra tilt angles range from 12–13°. In the eighth O2- site, O2- is bonded to five Ca2+ and one Ni2+ atom to form distorted OCa5Ni octahedra that share corners with four OCa3Ni2 square pyramids, corners with two OCaNi3 tetrahedra, edges with four OCa5Ni octahedra, edges with six OCa3Ni2 square pyramids, and an edgeedge with one OCaNi3 tetrahedra.

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↗