Al2GeO4(OH)2: Rietveld refinement and stereochemical discussion

Abstract

Abstract The structure of Al2GeO4(OH)2 [C2/c; a = 5.4197(3) Å, b = 8.2464(3) Å, c = 9.3187(3) Å, β = 110.933(3); Z = 4] was refined by X-ray Rietveld methods. It contains GeO4 tetrahedra having all four O atoms in common with an AlO2OH framework built from AlO4(OH)2 octahedra sharing three edges. The H atom could be located only approximately. The coordinations of the atoms are mostly as in topaz, Al2SiO4(F,OH)2, and its synthetic OH endmember, but the arrangement of the oxygen atoms is that of a distorted cubic close-packing, while in topaz it is based on a close-packing of the type ABAC.