Glass Formation and Properties in the System Calcia-Gallia-Germania

The critical cooling rate for glass formation, R^c, was measured for four compositions in the system calcia-gallia-germania. The activation energy, E, and frequency factor, u, for the crystallization process were determined by reheating the glasses at varied constant heating rates and measuring the temperature of crystallization. Both E and v increased, with increasing germania content of the glass, whereas R^c decreased. The density, refractive index, and Abbe number were also measured; all decreased with increasing GeO² content. These results are compared with those for calcia-gallia-silica glasses of comparable compositions.