Materials Data on Cr7Se8 by Materials Project
Cr7Se8 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are four inequivalent Cr+2.29+ sites. In the first Cr+2.29+ site, Cr+2.29+ is bonded to six Se2- atoms to form a mixture of edge, face, and corner-sharing CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 49–51°. There are two shorter (2.65 Å) and four longer (2.66 Å) Cr–Se bond lengths. In the second Cr+2.29+ site, Cr+2.29+ is bonded to six Se2- atoms to form a mixture of edge, face, and corner-sharing CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 47–50°. There are a spread of Cr–Se bond distances ranging from 2.60–2.69 Å. In the third Cr+2.29+ site, Cr+2.29+ is bonded to six Se2- atoms to form a mixture of edge, face, and corner-sharing CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 48–51°. There are a spread of Cr–Se bond distances ranging from 2.57–2.71 Å. In the fourth Cr+2.29+ site, Cr+2.29+ is bonded to six Se2- atoms to form a mixture of edge, face, and corner-sharing CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 47–51°. There are a spread of Cr–Se bond distances ranging from 2.57–2.75 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to five Cr+2.29+ atoms to form a mixture of distorted edge and corner-sharing SeCr5 square pyramids. In the second Se2- site, Se2- is bonded in a 6-coordinate geometry to six Cr+2.29+ atoms. In the third Se2- site, Se2- is bonded to five Cr+2.29+ atoms to form a mixture of distorted edge and corner-sharing SeCr5 trigonal bipyramids.