REACTION-KINETICS OF SIO2 AND ZNO-SIO2 SOL-GEL SOLUTIONS

Some silica sols prepared from tetraethoxysilane (TEOS) and various am ounts of water (molar ratios H2O:TEOS = r(w) = 2-9.6) were tested with regard to their suitability as starting materials for zinc dopant sol s. The influence of composition and of preparation conditions on struc ture were determined by viscosimetric measurements and by the molybdat e method (the colorimetric observation of the acidic depolymerization of the silicate network of the colloidal particles). It is shown that the structure of the sols depends not only on the chemical composition but also on applied heat treatments.