Thermoelasticity of (Mg,Fe)SiO3 perovskite

Thursday, 18 December 2014
Han Hsu1, Gaurav Shukla2, Zhongqing Wu3, Matteo Cococcioni4 and Renata M Wentzcovitch2, (1)National Central University, Department of Physics, Jhongli City, Taiwan, (2)University of Minnesota Twin Cities, Minneapolis, MN, United States, (3)USTC University of Science and Technology of China, School of Earth and Space Sciences, Hefei, China, (4)University of Minnesota, Minneapolis, MN, United States
We present first-principles calculations based on LDA+U of high temperature elastic properties of (Mg1-xFe2+x)SiO3 bridgemanite (0 < x < 0.125). Calculated aggregate elastic moduli and acoustic velocities for the Mg-end member (x=0) are in excellent agreement with the latest high pressure and high temperature measurements. Consequences of the pressure induced iron displacement that results in an increase in iron Mössbauer quadrupole splitting (QS) are also investigated. The main difference on the elastic properties of these states is a softening of the shear modulus by ~1% when iron occupies the high-QS site. However, some other elastic anomalies exist when both iron states co-exist.