The devitrification kinetics of transparent silica glass prepared by gel-casting method

Resumo

The kinetics of the crystallization of cristobalite in the amorphous silica glass were studied for samples
prepared by gel-casting and sintering in air. Avrami and rate equations were used to calculate the rate
constants and the activation energy. The results showed that the crystallization obeys the first order and
occurs mainly on the surface with activation energy of 543-546kJ/mol. The fewer amounts of OH-groups and
the high amount of oxygen vacancies are expected to stand behind the increase in the activation energy as
compared with that reported in literatures.
Keywords: Devitrification, Gel-Casting, Silica Glass, Cristobalite, Crystallization.