Crystal structure and thermoelastic properties of (Mg0.91Fe0.09)SiO3 postperovskite up to 135 GPa and 2,700 K.

ABSTRACT: Intriguing seismic observations have been made for the bottom 400 km of Earth's mantle (the D'' region) over the past few decades, yet the origin of these seismic structures has not been well understood. Recent theoretical calculations have predicted many unusual changes in physical properties across the postperovskite transition, perovskite (Pv) --> postperovskite (PPv), that may provide explanations for the seismic observations. Here, we report measurements of the crystal structure of (Mg(0.91)Fe(0.09))SiO(3)-PPv under quasi-hydrostatic conditions up to the pressure (P)-temperature (T) conditions expected for the core-mantle boundary (CMB). The measured crystal structure is in excellent agreement with the first-principles calculations. We found that bulk sound speed (V(Phi)) decreases by

SUBMITTER: Shim SH 

PROVIDER: S-EPMC2396716 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature