Materials Data on CaFe2(AsO5)2 by Materials Project

Abstract

CaFe2(AsO5)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ca is bonded to six O atoms to form CaO6 octahedra that share corners with four equivalent FeO6 octahedra and corners with six equivalent AsO4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. There are two shorter (2.40 Å) and four longer (2.47 Å) Ca–O bond lengths. Fe is bonded to six O atoms to form FeO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with four equivalent AsO4 tetrahedra, and edges with two equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are a spread of Fe–O bond distances ranging from 1.87–2.08 Å. As is bonded to four O atoms to form AsO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with four equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 47–66°. There are a spread of As–O bond distances ranging from 1.68–1.77 Å. There are four inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Ca and one As atom. In the second O site, O is bonded in a trigonal planar geometry to one Ca, one Fe, and one As atom. In the third O site, O is bonded in a water-like geometry to two equivalent Fe atoms. In the fourth O site, O is bonded in a 3-coordinate geometry to two equivalent Fe and one As atom.