Raman spectrum of synthetic zircon (ZrSiO4) and thorite (ThSiO4)

The complete Raman spectra of single-crystal synthetic zircon and thorite are reported for the first time. Results are presented for thorite at 295K and zircon at 295 and 90K. The temperature-dependent study was essential for distinguishing between weak first-order bands and second-order features which can have narrow half-widths. The lattice vibrations in both crystals are notably harmonic. The spectra are analysed in terms of internal and lattice modes of the SiO44- complex with some success. The crystal-field splittings for the internal modes are large. A comparison between the zircon and thorite results enables an assignment to be made of the Raman spectrum of powdered hafnon (HfSiO4) reported by Nicola and Rutt (1974).