GARNET-LIKE STRUCTURES OF HIGH-PRESSURE CADMIUM GERMANATE AND CALCIUM GERMANATE

Crystals of CdGeO3 grown at a pressure of 65 kilobars are tetragonal and have an ordered, garnet-like crystal structure with cadmium occupying the dodecahedral and octahedral sites, and germanium the octahedral and tetrahedral sites. The crystal structure (a = 12.406 ± 1 angstroms, c = 12.256 ± 1 angstroms, and space group I41/a) has been refined by least-squares analysis to an R (discrepancy index) of 0.073. Two high-pressure phases of CaGeO3 were synthesized, one isotypic with tetragonal CdGeO3 (a = 12.514 ± 3 angstroms, c = 12.358 ± 3 angstroms), and the other isotypic with perovskite.