Anomalous sound velocities in polycrystalline MgO under non-hydrostatic compression

Abstract

Brillouin scattering from polycrystalline MgO (periclase) non-hydrostatically compressed to, and decompressed from, 60 GPa at room temperature documents shear- and compressional-wave velocities ∼20% lower than values measured under hydrostatic compression. Calculations reveal that wave velocities can be lowered due to the elastic effects of non-hydrostatic stresses, but by only a few percent. Neither these elastic effects nor preferred orientation can account for the reduction in the sound velocity. Copyright 2011 by the American Geophysical Union.