Materials Data on Cr5Cu(GeO6)2 by Materials Project

Abstract

Cr5Cu(GeO6)2 is beta indium sulfide-derived structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are three inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent CuO4 tetrahedra, corners with four equivalent GeO4 tetrahedra, and edges with four CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 2.01–2.05 Å. In the second Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with three equivalent CuO4 tetrahedra, corners with three equivalent GeO4 tetrahedra, and edges with five CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.97–2.13 Å. In the third Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent CuO4 tetrahedra, corners with four equivalent GeO4 tetrahedra, and edges with six CrO6 octahedra. There are two shorter (1.97 Å) and four longer (2.07 Å) Cr–O bond lengths. Cu1+ is bonded to four O2- atoms to form CuO4 tetrahedra that share corners with twelve CrO6 octahedra. The corner-sharing octahedra tilt angles range from 59–62°. There are two shorter (2.06 Å) and two longer (2.10 Å) Cu–O bond lengths. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with nine CrO6 octahedra. The corner-sharing octahedra tilt angles range from 51–57°. There are a spread of Ge–O bond distances ranging from 1.76–1.89 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Cr3+ and one Ge4+ atom. In the second O2- site, O2- is bonded to three Cr3+ and one Cu1+ atom to form distorted corner-sharing OCr3Cu tetrahedra. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Cr3+ and one Ge4+ atom. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Cr3+ and one Ge4+ atom. In the fifth O2- site, O2- is bonded to three Cr3+ and one Cu1+ atom to form a mixture of distorted edge and corner-sharing OCr3Cu tetrahedra.