Infrared and Raman study of some heteropolyacid hydrates

Infrared and Raman spectra of hydrates od 12-molybdophosphonic, 12-tungstophosphonic and 12-silicotungstenic acid have been investigated over a wide temperature range. Three types of protonic entities H3O+, H2O and OH groups attached to the skeleton have been shown to exist and there is a temperature dependent dynamic equilibrium between various species. The structural disorder and the conductivity mechanism in these superionic protonic conductors are discussed.