Thermal structural transitions of amorphous silicon dioxide prepared by the sol-gel process in different reaction media

Thermal changes of the true density and polymorphous transitions of amorpho us silicon dioxide prepared from tetraethoxysilane by the sol-gel process w ere studied as influenced by the nature of reaction medium and the H2O : Si (OC2H5)(4) ratio. The nature of reaction medium (organic solvent) is one of the most important parameters affecting the polymorphous transitions and c hanges of SiO2 density on heating to 1573 K.