Influence of Reaction Conditions on Sol-Gel Process Producing SiO 2 and SiO 2- P 2 O 5 Gel and Glass

Abstract

The effect of H2O and the slow thermal annealing on the properties of pure silica (SiO2) and phos- phosilicate (SiO2-P2O5) gel-glasses are presented. The monolithic samples have been prepared via sol-gel process using tetraethorthosilicate (TEOS), Si(C2H5O)4 and Triethylphosphate (TEP) (C2H5O)3P(O) as SiO2 and P2O5 precursors. Phosphate incorporates into the silicate network by substituting Si atoms and consequently, we observed changes in structural and spectroscopic properties for these systems. The structures of prepared samples were examined by observed weight loss, XRD and FTIR. It has been found that in the structure of pure silica and phosphosili- cate glasses there are formed domains characterized by certain degree of ordering of the units present in their composition, while the structure of pure silica is still amorphous of these glasses. The changing character of domains structure may be the reason of different chemical activities of phosphosilicate glass.