Synthesis, Raman and Rietveld analysis of thorium diphosphate

We report the synthesis of thorium diphosphate ThP2O7 and its study by Raman spectroscopy and Rietveld analysis. This compound has been found to be closely related to the zirconium diphosphate type, with space group Pa-3 and a=8.7601(3) Å. No superstructure was observed. The metastability of ThP2O7 appears to stem from the six-fold oxygen environment of ThIV, a unique case in the structural chemistry of this cation.