The behaviour of alpha -quartz and pressure-induced SiO₂ glass under pressure: a molecular dynamical study

Abstract

The authors have carried out extensive molecular dynamical calculations on alpha -quartz and pressure-induced glass and have related these to the experimental observations under static and shock pressure loading. In the crystalline quartz, densification and amorphization take place sharply around 20 GPa and are related to the changes in the Si coordination. The pressure-induced glass is considerably less compressible than the fused silica, showing a gradual change in the Si coordination, and is unlike the glass studied earlier by Tse, Klug and Le Page (1992). However even this glass shows a densification, similar to that of quartz as well as fused silica. Retrieval of the four-coordinated state, in both cases, requires annealing at high temperatures. Just before amorphization of alpha -quartz, O atoms are still far from the recently proposed BCC packing.