Materials Data on CaCu(GeO3)2 by Materials Project

Abstract

CaCuGe2O6 is Esseneite structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.75 Å. Cu2+ is bonded to six O2- atoms to form CuO6 octahedra that share corners with six equivalent GeO4 tetrahedra and edges with two equivalent CuO6 octahedra. There are a spread of Cu–O bond distances ranging from 1.99–2.29 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent CuO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–61°. There are a spread of Ge–O bond distances ranging from 1.74–1.84 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+ and two equivalent Ge4+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Cu2+, and one Ge4+ atom. In the third O2- site, O2- is bonded to one Ca2+, two equivalent Cu2+, and one Ge4+ atom to form a mixture of distorted edge and corner-sharing OCaCu2Ge tetrahedra.