Pressure-amorphizedSiO2α-quartz: An anisotropic amorphous solid

Abstract
Recent experiments [Kruger and Jeanloz, Science 249, 647 (1990)] have shown that the pressure-induced amorphous form of AlPO4 reverts to its original ‘‘single-crystal’’ form on release of pressure. Here we present the results of a Brillouin scattering study of the sister compound α-quartz, SiO2 (which can also be pressure amorphized but retains its amorphous structure on release of pressure), which shows that the recovered material is not elastically isotropic but retains a ‘‘memory’’ of its original crystallographic orientation.