Materials Data on Sm2Ge2O7 by Materials Project

Abstract

Sm2Ge2O7 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Sm3+ is bonded to eight O2- atoms to form distorted SmO8 hexagonal bipyramids that share edges with six equivalent SmO8 hexagonal bipyramids and edges with six equivalent GeO6 octahedra. There are two shorter (2.20 Å) and six longer (2.53 Å) Sm–O bond lengths. Ge4+ is bonded to six equivalent O2- atoms to form GeO6 octahedra that share corners with six equivalent GeO6 octahedra and edges with six equivalent SmO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 46°. All Ge–O bond lengths are 1.96 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Sm3+ and two equivalent Ge4+ atoms. In the second O2- site, O2- is bonded to four equivalent Sm3+ atoms to form corner-sharing OSm4 tetrahedra.