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Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
CaCo2O4 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 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.67 Å. In the second Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.68 Å. There are four inequivalent Co3+ sites. In the first Co3+ site, Co3+ is bonded to five O2- atoms to form CoO5 square pyramids that share corners with four CoO6 octahedra and edges with two equivalent CoO5 square pyramids. The corner-sharing octahedra tilt angles range from 53–54°. There are a spread of Co–O bond distances ranging from 1.84–2.01 Å. In the second Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four CoO5 square pyramids and edges with four CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.86–2.00 Å. In the third Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four CoO5 square pyramids and edges with four CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.86–2.00 Å. In the fourth Co3+ site, Co3+ is bonded to five O2- atoms to form CoO5 square pyramids that share corners with four CoO6 octahedra and edges with two equivalent CoO5 square pyramids. The corner-sharing octahedra tilt angles range from 53–54°. There are a spread of Co–O bond distances ranging from 1.85–2.00 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three Co3+ atoms. In the second O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form distorted OCaCo3 trigonal pyramids that share corners with two equivalent OCa2Co3 square pyramids, corners with two equivalent OCaCo3 trigonal pyramids, and edges with three OCa2Co3 square pyramids. In the third O2- site, O2- is bonded to one Ca2+ and three Co3+ atoms to form distorted OCaCo3 trigonal pyramids that share corners with two equivalent OCa2Co3 square pyramids, corners with two equivalent OCaCo3 trigonal pyramids, and edges with three OCa2Co3 square pyramids. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to three Co3+ atoms. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to four Ca2+ and two equivalent Co3+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Ca2+ and three Co3+ atoms to form OCa2Co3 square pyramids that share corners with two equivalent OCaCo3 trigonal pyramids, edges with four OCa2Co3 square pyramids, and edges with three OCaCo3 trigonal pyramids. In the seventh O2- site, O2- is bonded in a 6-coordinate geometry to four Ca2+ and two equivalent Co3+ atoms. In the eighth O2- site, O2- is bonded to two equivalent Ca2+ and three Co3+ atoms to form OCa2Co3 square pyramids that share corners with two equivalent OCaCo3 trigonal pyramids, edges with four OCa2Co3 square pyramids, and edges with three OCaCo3 trigonal pyramids.
CaCo2O4 is Spinel structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Ca2+ is bonded to four equivalent O2- atoms to form CaO4 tetrahedra that share corners with twelve equivalent CoO6 octahedra. The corner-sharing octahedral tilt angles are 62°. All Ca–O bond lengths are 2.15 Å. Co3+ is bonded to six equivalent O2- atoms to form CoO6 octahedra that share corners with six equivalent CaO4 tetrahedra and edges with six equivalent CoO6 octahedra. All Co–O bond lengths are 1.96 Å. O2- is bonded to one Ca2+ and three equivalent Co3+ atoms to form a mixture of edge and corner-sharing OCaCo3 tetrahedra.
CaCo2O4 is Spinel structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Ca2+ is bonded to four equivalent O2- atoms to form CaO4 tetrahedra that share corners with twelve equivalent CoO6 octahedra. The corner-sharing octahedra tilt angles range from 55–64°. All Ca–O bond lengths are 2.20 Å. Co3+ is bonded to six equivalent O2- atoms to form distorted CoO6 octahedra that share corners with six equivalent CaO4 tetrahedra and edges with six equivalent CoO6 octahedra. There are four shorter (1.91 Å) and two longer (2.39 Å) Co–O bond lengths. O2- is bonded in a 4-coordinate geometry to one Ca2+ and three equivalent Co3+ atoms.