Elasticity and strength of calcium silicate perovskite at lower mantle pressures
Abstract
CaSiO _{3} perovskite was synthesized in a diamond cell and its lattice strain anisotropy was measured under nonhydrostatic compression to conditions corresponding to 61 GPa. Experiments were performed using energy dispersive synchrotron Xray diffraction in a radial geometry. The equation of state of CaSiO _{3} perovskite obtained from lattice strains measured at different angles from the loading direction can describe the range of compression curves previously reported under quasihydrostatic and nonhydrostatic conditions. The ratio of the differential stress to the shear modulus increases from 0.016(5) to 0.039(4) for CaSiO _{3} perovskite over pressures from 19 to 61 GPa. In combination with a theoretical prediction for the shear modulus, roomtemperature yield strengths are 311 GPa for CaSiO _{3} perovskite over this pressure range. Under the assumption that the effect of the tetragonal distortion is minimal, the elastic constants for CaSiO _{3} perovskite were recovered. Singlecrystal elastic constants of CaSiO _{3} perovskite are in good agreement with theoretical predictions for the cubic phase. In particular, the elastic anisotropy, S, decreases from 0.0020(7) to 0.0004(2) GPa ^{1} over the 1961 GPa pressure range. Comparison with theoretical elasticity data provides evidence for possible strength anisotropy.
 Publication:

Physics of the Earth and Planetary Interiors
 Pub Date:
 June 2004
 DOI:
 10.1016/j.pepi.2003.10.006
 Bibcode:
 2004PEPI..143...93S