Materials Data on Cr(FeSe2)2 by Materials Project

Cr(FeSe2)2 crystallizes in the monoclinic Cm 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 two equivalent CrSe6 octahedra, edges with four equivalent FeSe6 octahedra, and a faceface with one FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 52–53°. There are a spread of Cr–Se bond distances ranging from 2.46–2.60 Å. There are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with six equivalent CrSe6 octahedra, corners with six equivalent FeSe6 octahedra, edges with two equivalent FeSe6 octahedra, a faceface with one CrSe6 octahedra, and a faceface with one FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 50–53°. There are a spread of Fe–Se bond distances ranging from 2.44–2.55 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with six equivalent FeSe6 octahedra, edges with two equivalent FeSe6 octahedra, edges with four equivalent CrSe6 octahedra, and a faceface with one FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 50–52°. There are a spread of Fe–Se bond distances ranging from 2.44–2.60 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to one Cr3+ and four Fe+2.50+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent Cr3+ and three Fe+2.50+ atoms. In the third Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Cr3+ and two Fe+2.50+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to one Cr3+ and three Fe+2.50+ atoms.