Influence of Temperature and Anisotropic Pressure on the Phase Transitions in α-Cristobalite

Abstract

The role of temperature and anisotropy of the applied load in the pressure–induced transformations of α -cristobalite is investigated by means of first principles molecular dynamics combined with the metadynamics algorithm for the study of solid-solid phase transitions. We reproduce the transition to α-PbO2 as found in experiments and we observe that the transition paths are qualitatively different and yield different products when a nonhydrostatic load is applied, giving rise to a new class of metastable structures with mixed tetrahedral and octahedral coordination.