INELASTIC NEUTRON-SCATTERING STUDY OF PROTONIC SPECIES DURING THE THERMAL DEHYDRATION OF 12-TUNGSTOPHOSPHORIC HEXAHYDRATE

12-Tungstophosphoric acid hexahydrate and its derivatives dehydrated a t 473, 573 and 873 K have been studied by incoherent inelastic neutron scattering. Comparison is made with the sodium salts of this compound . Sharp spectra assigned to H5O2+ species (hexahydrate at 25 K), H3O(473 K dehydrated) and a lone proton (573 K) have been obtained. Proto ns fixed to the host lattice are possible minor species in the hexahyd rate and in the material dehydrated at 573 K. The strong background ab ove 300 cm-1 in the hexahydrate and above 50 cm-1 in the dehydrated ma terials may indicate the presence of mobile protons (proton gas).