HR: 1340h
AN: MR23A-0043 [Abstracts]
TI: Composition Dependence of Pressure-Induced Spin Transitions in the (Mg,Fe)SiO3 System
AU: * Berta, A
EM: akberta@wisc.edu
AF: University of Wisconsin - Madison, 201 A MSE, 1509 University Ave, Madison, WI 53706
United States
AU: Persson, K
EM: kpersson@mit.edu
AF: Massachusetts Institute of Technology, 13-4057
77 Massachusetts Ave, Boston, MA 02139
United States
AU: Ceder, G
EM: gceder@mit.edu
AF: Massachusetts Institute of Technology, 13-4057
77 Massachusetts Ave, Boston, MA 02139
United States
AU: Morgan, D
EM: ddmorgan@wisc.edu
AF: University of Wisconsin - Madison, 201 A MSE, 1509 University Ave, Madison, WI 53706
United States
AB:
Recent experimental results suggest that Fe undergoes a high-spin to low-spin transition in both the rocksalt and perovskite
phases at lower mantle pressures. These spin transitions may have a profound impact on the properties of lower mantle
phases. In this work the critical spin-transition pressure for Fe in perovskite (Mg,Fe)SiO3 is calculated using ab
initio methods. We focus in particular on the alloy nature of the material, studying the spin-transition pressure for
varying concentrations of Fe. The results show that as the concentration of Fe increases, the transition pressure decreases.
This is directly opposite the trend observed for spin transition pressures found in rocksalt (Mg,Fe)O. The difference in
trends in spin-transition pressure is explained by the role of octahedral tilting in the perovskite structure.
DE: 0599 General or miscellaneous
DE: 1025 Composition of the mantle
DE: 3924 High-pressure behavior
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005