STRUCTURE AND PROPERTIES OF TiO₂-SiO₂ AND TiO₂-GeO₂ GLASSES

Abstract

The coordination of Ti4+ ions in the low expansion TiO2-SiO2 glasses made from metal alkoxides by the sol-gel technique and TiO2-GeO2 glasses made by melting was investigated on the basis of the observation of crystallization behavior and the infrared spectroscopy. The α-cristobalite type SiO2 and α-quartz type GeO2 crystals containing 4-fold coordinated Ti4+ ions precipitated in the TiO2-SiO2 and TiO2-GeO2 glasses. Infrared spectra of the glasses were very similar to the corresponding crystallized products. These facts suggest that the Ti4+ ions in the TiO2-SiO2 glasses are 4-fold coordinated with oxygens as in the glasses made by the high temperature flamespray technique, and that Ti4+ ions in the TiO2-GeO2 glasses are also in 4-fold coordination.