Microstructural evolution of TiO₂-doped silica gels during heating

Abstract

Properties of silica glass, doped with TiO₂, obtained by the sol-gel technique were examined as depending on the heating method, using the microstructural investigation methods. It has been found that the greatest specific surface and porosity are obtained immediately after the removal of water and organic substances at the temperature of about 300 °C. With increasing heating temperature the specific surface and the porosity decrease, especially above 900 °C. The mode the pores are Hnked with each other is also changed. The pores assume the character of "through-pores", open at both ends, and their closing takes place only with the lapse of time. The heating rate does not exert any essential influence on the product properties after heating, nevertheless slow heating favours the preservation of the primary microstructure of gel.