Materials Data on CaFe2CoO7 by Materials Project

Abstract

CaFe2CoO7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.40–2.84 Å. In the second Ca site, Ca is bonded to seven O atoms to form distorted CaO7 pentagonal bipyramids that share corners with three equivalent FeO4 tetrahedra, corners with four FeO5 trigonal bipyramids, edges with two CoO6 octahedra, and edges with two equivalent FeO6 pentagonal pyramids. There are a spread of Ca–O bond distances ranging from 2.30–2.48 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded to four O atoms to form FeO4 tetrahedra that share corners with three CoO6 octahedra, corners with three equivalent CaO7 pentagonal bipyramids, and a cornercorner with one FeO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of Fe–O bond distances ranging from 1.80–1.90 Å. In the second Fe site, Fe is bonded to five O atoms to form FeO5 trigonal bipyramids that share corners with two equivalent CoO6 octahedra, corners with two equivalent CaO7 pentagonal bipyramids, a cornercorner with one FeO5 trigonal bipyramid, and an edgeedge with one FeO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 40–45°. There are a spread of Fe–O bond distances ranging from 1.81–1.96 Å. In the third Fe site, Fe is bonded to six O atoms to form distorted FeO6 pentagonal pyramids that share corners with two equivalent CoO6 octahedra, a cornercorner with one FeO4 tetrahedra, edges with two equivalent CoO6 octahedra, edges with two equivalent CaO7 pentagonal bipyramids, and edges with two FeO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 28–44°. There are a spread of Fe–O bond distances ranging from 1.96–2.11 Å. In the fourth Fe site, Fe is bonded to five O atoms to form distorted FeO5 trigonal bipyramids that share corners with three CoO6 octahedra, corners with two equivalent CaO7 pentagonal bipyramids, a cornercorner with one FeO5 trigonal bipyramid, an edgeedge with one CoO6 octahedra, and an edgeedge with one FeO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 23–50°. There are a spread of Fe–O bond distances ranging from 1.90–2.12 Å. There are two inequivalent Co sites. In the first Co site, Co is bonded to six O atoms to form CoO6 octahedra that share a cornercorner with one FeO4 tetrahedra, corners with four FeO5 trigonal bipyramids, an edgeedge with one CoO6 octahedra, an edgeedge with one CaO7 pentagonal bipyramid, and edges with two equivalent FeO6 pentagonal pyramids. There are a spread of Co–O bond distances ranging from 1.81–2.04 Å. In the second Co site, Co is bonded to six O atoms to form CoO6 octahedra that share corners with two equivalent FeO6 pentagonal pyramids, corners with two equivalent FeO4 tetrahedra, a cornercorner with one FeO5 trigonal bipyramid, an edgeedge with one CoO6 octahedra, an edgeedge with one CaO7 pentagonal bipyramid, and an edgeedge with one FeO5 trigonal bipyramid. There are a spread of Co–O bond distances ranging from 1.77–1.96 Å. There are fourteen inequivalent O sites. In the first O site, O is bonded in a 1-coordinate geometry to two Ca and one Fe atom. In the second O site, O is bonded to two Ca, one Fe, and one Co atom to form distorted corner-sharing OCa2FeCo tetrahedra. In the third O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Fe, and one Co atom. In the fourth O site, O is bonded to one Ca, two Fe, and one Co atom to form distorted OCaFe2Co tetrahedra that share corners with two OCa2FeCo tetrahedra and an edgeedge with one OCaFe2Co tetrahedra. In the fifth O site, O is bonded in a 3-coordinate geometry to one Ca, one Fe, and one Co atom. In the sixth O site, O is bonded in a 4-coordinate geometry to one Ca, one Fe, and two Co atoms. In the seventh O site, O is bonded in a distorted trigonal non-coplanar geometry to one Ca, one Fe, and one Co atom. In the eighth O site, O is bonded in a distorted trigonal planar geometry to two Ca and one Fe atom. In the ninth O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and two Fe atoms. In the tenth O site, O is bonded in a 3-coordinate geometry to one Ca and two Fe atoms. In the eleventh O site, O is bonded in a distorted T-shaped geometry to one Fe and two Co atoms. In the twelfth O site, O is bonded to one Ca, two Fe, and one Co atom to form distorted OCaFe2Co tetrahedra that share corners with three OCa2FeCo tetrahedra and an edgeedge with one OCaFe2Co tetrahedra. In the thirteenth O site, O is bonded in a 4-coordinate geometry to one Ca, two Fe, and one Co atom. In the fourteenth O site, O is bonded in a distorted trigonal non-coplanar geometry to two Fe and one Co atom.