In the course of the preparation of WO3 by sol-gel technique we have studie
d kinetics of its synthesis and the structural changes during gelation. In-
situ Raman scattering spectra were obtained for a series of samples during
the transition from aqueous solution to gel. The changes in the Raman featu
res were monitored as a function of time during gelation. The removal of wa
ter molecules affects the symmetric W=O stretching mode. The Raman spectrum
of a gelified sample shows peaks attributed to the O-W-O bending mode and
the disappearance of the high-frequency mode attributed to polyanionic spec
ies. After two days the gelified sample became a precipitated material, whi
ch exhibited the Raman spectrum of a crystalline tungsten oxide hydrate.