HR: 1340h
AN: MR23C-1525    [Abstracts]
TI: Electrical conductivity of FeSi under pressure
AU: * Verstraete, M
EM: mjv500@york.ac.uk
AF: Dept. of Physics, University of York, Heslington, YO10 5DD York, Heslington, YO10 5DD, United Kingdom
AU: Caracas, R
EM: razvan.caracas@ens-lyon.fr
AF: Ecole Normale Superieure de Lyon, Laboratory of Earth Sciences UMR 5570 46, allee d'Italie, Lyon, 69364, France
AB: Chemical arguments suggest that FeSi can result from the reaction of the Fe-rich perovskite and post-perovskite in the D" layer with the Fe of the liquid core [1]. FeSi could thus accumulate in the lower parts of D", in particular the ultra-low velocity zones (ULVZ). Physical arguments (high density) and seismological arguments (low velocities) plead for its existence in these regions [2]. We compute the temperature-dependent electronic conductivity of FeSi from density-functional perturbation theory. From the phonons and electron-phonon coupling we solve the Boltzmann transport equations to the lowest order to give the electrical and thermal conductivities [3]. We find that the electrical resistivity of FeSi at lower mantle and outer core conditions is on the order of 3.5-4.0 micro Ohm m at 2500-3000K. This is about twice the resistivity of Fe in the same conditions, which is similar to the assumed resistivity of the outer core. If present in significant amounts, then the large values of the conductivity computed here suggest FeSi as the major conducting phase in the D" and ULVZ, and the mineral that would ensure the electromagnetic coupling between the mantle and the core. [1] E. Knittle and R. Jeanloz, Science, 251, 1438 (1991). [2] R. Caracas and R.M. Wentzcovitch, Geophys. Res. Lett. 31, No. 20, 10.1029/2004GL020601 (2004) [3] S.Y. Savrasov and D.Y. Savrasov, Phys. Rev. B, 54, 16487 (1996).
DE: 3621 Mantle processes (1038)
DE: 3914 Electrical properties
DE: 5109 Magnetic and electrical properties (0925)
DE: 5430 Interiors (8147)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting