Materials Data on Cr2FeSe4 by Materials Project
FeCr2Se4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Cr3+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with six equivalent FeSe6 octahedra, edges with six equivalent CrSe6 octahedra, and a faceface with one FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. There are a spread of Cr–Se bond distances ranging from 2.51–2.60 Å. Fe2+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with twelve equivalent CrSe6 octahedra, edges with two equivalent FeSe6 octahedra, and faces with two equivalent CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. There are two shorter (2.52 Å) and four longer (2.59 Å) Fe–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to three equivalent Cr3+ and one Fe2+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to three equivalent Cr3+ and two equivalent Fe2+ atoms.