Materials Data on Mg2Ge2O5 by Materials Project

Abstract

Mg2Ge2O5 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Mg–O bond lengths are 2.39 Å. In the second Mg2+ site, Mg2+ is bonded to twelve O2- atoms to form MgO12 cuboctahedra that share corners with four equivalent MgO12 cuboctahedra, faces with four equivalent MgO12 cuboctahedra, and faces with eight equivalent GeO5 square pyramids. There are eight shorter (2.61 Å) and four longer (2.74 Å) Mg–O bond lengths. Ge3+ is bonded to five O2- atoms to form GeO5 square pyramids that share corners with five equivalent GeO5 square pyramids and faces with four equivalent MgO12 cuboctahedra. There is one shorter (1.86 Å) and four longer (1.94 Å) Ge–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four Mg2+ and two equivalent Ge3+ atoms to form a mixture of distorted edge, corner, and face-sharing OMg4Ge2 octahedra. The corner-sharing octahedra tilt angles range from 0–70°. In the second O2- site, O2- is bonded in a linear geometry to four equivalent Mg2+ and two equivalent Ge3+ atoms.