J. Brodholt

A knowledge of how iron affects on the properties of mantle minerals is essential for ... of ferric and ferrous iron bearing perovskites and post-perovskites. In.
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Ab Initio Calculations on the Properties of Fe Bearing Perovskite and Post-perovskite Phases J. BRODHOLT, S. STACKHOUSE, M. ALFREDSSON, L. LI, D. WEIDNER, D. PRICE University College London Dept. of Earth Sciences, London UK

A knowledge of how iron affects on the properties of mantle minerals is essential for understanding many fundamental deep Earth processes. For instance the concentration of iron in the mantle, its partitioning between different phases, the Fe3+/Fe2+ ratio, and its spin state all affect the physical elastic and transport properties of the mantle. Among other things, the properties of Fe bearing minerals are essential, therefore, for a) interpreting seismic data on the mantle in terms of variations in composition, mineralogy and temperature, b) understanding heat flow through the effect iron has on the radiative part of heat transfer, and c) constraining the electrical conductivity of the mantle which, in turn, has implications for electromagnetic coupling between the core and mantle. We have, therefore, used ab initio DFT methods to examine the properties of ferric and ferrous iron bearing perovskites and post-perovskites. In particular we have looked at the pure FeSiO3 end-members as well as phases containing 6% and 12% iron, and in addition we have calculated the properties of perovskites containing both Fe3+ and Al3+. We have paid particular care in constraining the correct spin state as a function of pressure since we have found that the spin state is particularly sensitive to small amounts of non-hydrostatic strain. The results of these calculations and implications for the mantle will be presented.