Materials Data on CaCr4O8 by Materials Project

Abstract

CaCr4O8 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ca2+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All Ca–O bond lengths are 2.41 Å. There are two inequivalent Cr+3.50+ sites. In the first Cr+3.50+ site, Cr+3.50+ is bonded to six O2- atoms to form edge-sharing CrO6 octahedra. There is two shorter (1.95 Å) and four longer (1.98 Å) Cr–O bond length. In the second Cr+3.50+ site, Cr+3.50+ is bonded to six equivalent O2- atoms to form edge-sharing CrO6 octahedra. All Cr–O bond lengths are 2.04 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 Cr+3.50+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Cr+3.50+ atoms.