Single Crystal Elasticity of Iron Bearing Perovskite and Post Perovskite Analog

Abstract:

We measured single crystal elasticity of (1) pure and iron bearing MgSiO3 perovskite, and (2) Pbnm-CaIrO₃ and Cmcm-CaIrO_3, a representative analog of MgSiO3 perovskite and post perovskite, respectively, by means of inelastic X ray scattering at BL35XU, SPring-8.

The present results for MgSiO3 perovskite demonstrate that elastic anisotropy of magnesium perovskite is highly enhanced by iron incorporation. Furthermore anti-correlation between bulk sound velocity and shear wave velocity was confirmed with iron content, which is against the theoretical prediction. The anti-correlation found in this study is important, because it enables us to interpret the recent seismological observation of the anti-correlation in the deep lower mantle by means of iron content difference in perovskite.

On the other hand, we can learn difference of elasticity between perovskite and post perovskite thorough measurement on CaIrO3, as analog of MgSiO3 perovskite and post perovskite. From a characteristics of the single crystal elasticity of CaIrO3 compounds, we interpreted the texture pattern in the D” layer consistent with recent seismic observation.