Modified Spinel, Beta-Manganous Orthogermanate: Stability and Crystal Structure

Abstract

A new high-pressure polymorph with a modified spinel structure, β-Mn₂GeO₄, is stable in a pressure range intermediate between the field of the polymorph with the olivine structure and that of another high-pressure polymorph. Oxygen atoms are located approximately in cubic close packing with manganese and germanium atoms in octahedral and tetrahedral interstices, respectively, as in the spinel structure; however, germanium atoms form Ge₂O₇ groups instead of isolated GeO₄ groups.