Effect of Trace Impurities on Devitrification of Vitreous Silica

Abstract

Devitrification rates were measured for a series of vitreous silica glasses doped with trace levels of alkali metal oxide (1.6 to 57.8 molar ppm) and aluminum oxide (22 to 73.3 molar ppm). The devitrification rate varies inversely with the molar ratio of aluminum oxide to alkali metal oxide, a direct consequence of the effect of these trace impurities on viscosity .