Synchrotron x-ray diffraction study of the crystallisation kinetics of silica glass at high pressure and high temperature

Abstract

The crystallisation kinetics of silica glass have been studied within the stability field of stishovite by energy-dispersive x-ray diffraction with a synchrotron source and a cubic-anvil apparatus. Time-resolved diffraction patterns taken at every 50 to 200 s interval at a fixed temperature range from 600 to 900 °C and at a pressure of 10.5 GPa revealed that crystallisation into coesite and stishovite took place either in parallel or consecutively. Analyses with available kinetic equations showed that Avrami's expression fits the data the best, yielding activation energies of 12 ′ 0.3 kcal mol - 1 for crystallisation to coesite and 15 ′ 3 kcal mol - 1 to stishovite, respectively.