Glass transition temperature and devitrification behaviour of lithium-titanium-germanate glasses

The effect of replacing GeO2 by TiO2 on the glass-transition temperature and devitrification behaviour in lithium tetragermanate glass has been studied by differential thermal analysis, and Fourier-transform infrared spectra. The glass compositions are expressed by the general formula Li2OxTiO2(4-x)GeO2 with 0.00 less than or equal to x less than or equal to 1.00. The anion network of all glasses was found to contain GeO4 and GeO6 groups in the same molar ratio. The grass-transition and crystallisation temperature values are both increased by the progressive replacement of GeO2 by TiO2. Glasses with x < 0.5 devitrify into lithium tetragermanate crystals. Glasses with x greater than or equal to 0.5 devitrify in two steps into two non-identifiable phases. The influence on the crystallisation mechanisms of the specific surface of the samples was also pointed out. (C) 1997 Elsevier Science B.V.