CHARACTERIZATION OF VARIOUS STAGES OF THE SOL-GEL PROCESS

Monolithic samples of silica and cobalt-doped silica glasses were prepared from the hydrolysis-gelling process of TEOS in ethanol solution. Cobalt was used as a 'color indicator'. The sol-gel transition was studied by measuring the specific and intrinsic viscosities of the solution. The gel-glass transition was studied by infrared spectroscopy, TGA, DTA, density and BET measurements. The experiments indicate that the hydrolysis-gelling process is somewhat similiar to that of polycondensation of silicic acid and some degree of ordering must be present in the silica particles formed.