Etude infrarouge des orthosilicates et des orthogermanates-IV. Structures scheelite et zircon

The infrared spectrum (1400-70 cm-1) of orthogermanates and of some orthosilicates of tetravalent elements (Zr, Hf, Th, U, Ce) has been investigated. A fairly detailed assignment has been deduced from both group-theoretical considerations, and relationships between the observed frequencies and, either the mass, or the ionic radius of the tetravalent cations. Some correlations between the bending frequencies, the D2d local symmetry of the anion and the ionic radius of the cation are also discussed. © 1971.