Materials Data on Sr2MgGe2O7 by Materials Project
Sr2MgGe2O7 crystallizes in the tetragonal P-42_1m space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.59–2.91 Å. Mg2+ is bonded to four equivalent O2- atoms to form MgO4 tetrahedra that share corners with four equivalent GeO4 tetrahedra. All Mg–O bond lengths are 1.96 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one GeO4 tetrahedra and corners with two equivalent MgO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.74–1.82 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Sr2+ and two equivalent Ge4+ atoms to form a mixture of distorted edge and corner-sharing OSr2Ge2 tetrahedra. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+, one Mg2+, and one Ge4+ atom. In the third O2- site, O2- is bonded to three equivalent Sr2+ and one Ge4+ atom to form a mixture of distorted edge and corner-sharing OSr3Ge tetrahedra.