Materials Data on Ca2GeO4 by Materials Project

Abstract

Ca2GeO4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with eight CaO6 octahedra, corners with four equivalent GeO4 tetrahedra, edges with two equivalent CaO6 octahedra, and an edgeedge with one GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–67°. There are a spread of Ca–O bond distances ranging from 2.32–2.48 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with four equivalent CaO6 octahedra, corners with two equivalent GeO4 tetrahedra, edges with four CaO6 octahedra, and edges with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–67°. There are a spread of Ca–O bond distances ranging from 2.35–2.43 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with six CaO6 octahedra and edges with three CaO6 octahedra. The corner-sharing octahedra tilt angles range from 54–62°. There are a spread of Ge–O bond distances ranging from 1.77–1.81 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ca2+ and one Ge4+ atom. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Ca2+ and one Ge4+ atom. In the third O2- site, O2- is bonded to three Ca2+ and one Ge4+ atom to form distorted corner-sharing OCa3Ge trigonal pyramids.