New high-pressure transformation in α-quartz

Abstract

Recent experimental and theoretical studies report that quenched pressure-amorphized α-quartz is elastically anisotropic and displays a reversal of anisotropy with respect to the original crystallographic orientation. We demonstrate that samples recovered from static compression experiments of α-quartz exhibit an unusual pressure-induced microstructure, which arises from a new phase transformation in α-quartz at 21 GPa. Upon decompression, the high-pressure phase reverts to a quartzlike structure in a twinned state, accounting for the previously reported elastic behavior.