DOI: 10.17188/1322303
title: Materials Data on Ca(FeO2)2 by Materials Project

description: CaFe2O4 is Spinel-like structured and crystallizes in the triclinic P1 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 FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–69°. There are a spread of Ca–O bond distances ranging from 2.17–2.26 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.25–2.30 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 FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–69°. There are a spread of Ca–O bond distances ranging from 2.17–2.23 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 FeO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.23–2.32 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.28–2.31 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.27–2.34 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 FeO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.30 Å. In the eighth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.28–2.34 Å. There are sixteen inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.23 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.20 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.21 Å. In the fourth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–60°. There are a spread of Fe–O bond distances ranging from 1.91–2.06 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.94–2.18 Å. In the sixth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–60°. There are a spread of Fe–O bond distances ranging from 1.94–2.10 Å. In the seventh Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.02 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.18 Å. In the ninth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.04–2.18 Å. In the tenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.03 Å. In the eleventh Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.18 Å. In the twelfth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.20 Å. In the thirteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.20 Å. In the fourteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–60°. There are a spread of Fe–O bond distances ranging from 1.90–2.04 Å. In the fifteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.19 Å. In the sixteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Fe–O bond distances ranging from 1.94–2.13 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the second O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the third O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the sixth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the ninth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the eleventh O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 trigonal pyramids. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-fourth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form corner-sharing OCa2Fe2 tetrahedra. In the twenty-fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the thirtieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the thirty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the thirty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms.