Materials Data on Al2Co3GeO8 by Materials Project

Abstract

Co3Al2GeO8 is Spinel-derived structured and crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six equivalent CoO6 octahedra and corners with six equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 51–61°. There is two shorter (1.95 Å) and two longer (1.96 Å) Co–O bond length. In the second Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three equivalent CoO4 tetrahedra, corners with three equivalent GeO4 tetrahedra, edges with two equivalent CoO6 octahedra, and edges with four equivalent AlO6 octahedra. There are a spread of Co–O bond distances ranging from 2.02–2.17 Å. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three equivalent CoO4 tetrahedra, corners with three equivalent GeO4 tetrahedra, edges with two equivalent AlO6 octahedra, and edges with four equivalent CoO6 octahedra. There are a spread of Al–O bond distances ranging from 1.85–2.08 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with six equivalent CoO6 octahedra and corners with six equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 55–58°. There is two shorter (1.83 Å) and two longer (1.87 Å) Ge–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Co2+, two equivalent Al3+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Co2+, one Al3+, and one Ge4+ atom. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Co2+ and two equivalent Al3+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co2+ and one Al3+ atom.