Materials Data on Cr2CuSe3Br by Materials Project
CuCr2Se3Br is Spinel-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to six equivalent Se2- atoms to form CrSe6 octahedra that share corners with six equivalent CuSe3Br tetrahedra and edges with six equivalent CrSe4Br2 octahedra. All Cr–Se bond lengths are 2.54 Å. In the second Cr3+ site, Cr3+ is bonded to four equivalent Se2- and two equivalent Br1- atoms to form CrSe4Br2 octahedra that share corners with six equivalent CuSe3Br tetrahedra and edges with six CrSe6 octahedra. All Cr–Se bond lengths are 2.54 Å. Both Cr–Br bond lengths are 2.58 Å. Cu1+ is bonded to three equivalent Se2- and one Br1- atom to form CuSe3Br tetrahedra that share corners with twelve CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 53–61°. All Cu–Se bond lengths are 2.39 Å. The Cu–Br bond length is 2.62 Å. Se2- is bonded in a rectangular see-saw-like geometry to three Cr3+ and one Cu1+ atom. Br1- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Cr3+ and one Cu1+ atom.