SOL-GEL PROCESS

The term sol-gel is generally used to describe the preparation of ceramic materials starting from a colloidal suspension of solid particles in a liquid (sol) that then shifted to a gel state by means hydrolysis and polymerization process. The sol-gel process is characterized by a series of chemical reactions such as hydrolysis and condensation that occurs at room temperature due to the use of particular precursors like alcooxides, with general structure M(OR)z, where M is metal (generally silica), R is an alkylic group like (CxH2x+1) and “z” indicates the oxidation state. Among the most used precursors we can find TEOS (Si(OC2H5)4) and TMOS (Si(OCH3)4).