Crystallization kinetics of fluorosilicate glasses

Abstract

Crystallization kinetics and properties of fluorosilicate glasses containing 0 to 8 wt% fluorine have been studied. The effect of isothermal and non-isothermal heat treatments on the fraction crystallized has been investigated by the use of quantitative X-ray diffraction analysis and differential scanning calorimetry. A time-temperature-transformation diagram was constructed which shows a maximum rate of crystallization at about 650 °C. Activation energies of crystallization are found to be close to those for viscous flow which indicate similar mechanisms for both processes. The Avrami coefficients and other crystallization parameters have also been evaluated.