Crystal Structure of BaGe[Ge3O9]and Its Relation to Benitoite.

Abstract

BaGe[Ge3O9] is trigonal, space group P3, with lattice constants a = 11.61, c = 4.74 Å, and Z = 3. The structure was established by three-dimensional Patterson and electron density syntheses. Three-dimensional least-squares refinement resulted in a final R value of 6.8 percent (observed data only). The previously proposed structural relationship of this compound with benitoite, BaTiSi3O9, has been confirmed. The structure can be considered as composed of Ge3O9 rings, in which the Ge is tetrahedrally coordinated, linked through octahedrally coordinated Ge atoms to form a three-dimensional Ge-O network. All Ge polyhedra are linked by corner sharing. The Ba ions occupy positions in channels of the network.