Cadmiumphosphatsilicat Cd₅(PO₄)₂SiO₄und Cadmiumphosphatgermanat Cd₅(PO₄)₂GeO₄mit Silicocarnotitstruktur

Abstract

The structures of Cd5(PO4)2SiO4 and Cd5(PO4)2GeO4 have been determined by X-ray diffractometer data. Both compounds crystallize with the structure of silicocarnotite Ca5(PO4)2SiO4 (Dickens and Brown, 1971). Space group Pnma, Z = 4; Cd5(PO4)2SiO4: a = 669.2(2), b = 1499(1), c = 1014.0(5) pm; Cd5(PO4)2GeO4: a = 673.4(1), b = 1510.7(2), c = 1021.0(2) pm. The tetrahedral centers in position 4c are occupied exclusively by P, those in position 8d are occupied equally by P and Si (or Ge) in random distribution.