Vibrational spectra and H-bondings in anhydrous and monohydrate α-Zr phosphates

A new FTIR and FT-Raman investigation on α-zirconium phosphate (Zr(HPO4)2·H2O) and its anhydrous form has been performed in order to obtain an affordable assignment of their vibrational spectra as well as to highlight the hydrogen bonding structure formed by the P-OH groups and the intercalated water molecules. To this end the spectral changes induced by both temperature and isotopic exchange were observed on several high-purity grade samples of different morphology especially prepared and well characterized by SEM, RX, DSC and TGA. In particular, it is also presented as a detailed discussion of the results obtained by FTIR-PAS for different sample morphology. The observed spectra have been analyzed and interpreted according to the α-Zr(HPO4)2·H2O crystal structure and H-bond geometry. The obtained results allowed to clarify the mechanism of the α-Zr(HPO4)2·H2O→α-Zr(HPO4)2 dehydration process as well as the H-bonding changes involved in the high temperature phase transition of anhydrous α-Zr(HPO4)2.