Materials Data on Cr4Cu3Se8 by Materials Project
Cr4Cu3Se8 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are two inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with nine CuSe4 tetrahedra and edges with two equivalent CrSe6 octahedra. There are a spread of Cr–Se bond distances ranging from 2.52–2.57 Å. In the second Cr3+ site, Cr3+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of Cr–Se bond distances ranging from 2.51–2.75 Å. There are three inequivalent Cu+1.33+ sites. In the first Cu+1.33+ site, Cu+1.33+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with six equivalent CrSe6 octahedra and an edgeedge with one CuSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–60°. There are two shorter (2.39 Å) and two longer (2.52 Å) Cu–Se bond lengths. In the second Cu+1.33+ site, Cu+1.33+ is bonded to four Se2- atoms to form distorted CuSe4 tetrahedra that share corners with six equivalent CrSe6 octahedra, corners with two equivalent CuSe4 tetrahedra, and an edgeedge with one CuSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–55°. There are two shorter (2.35 Å) and two longer (2.46 Å) Cu–Se bond lengths. In the third Cu+1.33+ site, Cu+1.33+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with six equivalent CrSe6 octahedra and corners with two equivalent CuSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are two shorter (2.41 Å) and two longer (2.44 Å) Cu–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Cr3+ and one Cu+1.33+ atom to form a mixture of distorted edge and corner-sharing SeCr3Cu trigonal pyramids. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to three Cr3+ and two Cu+1.33+ atoms. In the third Se2- site, Se2- is bonded to three Cr3+ and one Cu+1.33+ atom to form a mixture of distorted edge and corner-sharing SeCr3Cu trigonal pyramids. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to three Cr3+ and two Cu+1.33+ atoms.