Institution: | a Department of Geological Sciences, University College London, Gower Street, WC1E 6BT London, UK b Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth, Germany |
Abstract: | The self-diffusivity of liquid iron has been measured between 2 and 20 GPa and 1883 and 2393 K. There is a large pressure dependence across the pressure range studied and simple Arrhenius extrapolation to outer core conditions yields unrealistically low diffusivities. The large pressure and temperature range covered, however, allows different a priori diffusion models to be tested using the experimental results. The free volume model J. Chem. Phys. 31 (1959) 1164] is found to be in excellent agreement with the experimental data and provides a basis for extrapolation of the results to outer core conditions. An extrapolation to core–mantle boundary (CMB) pressure at 4300 K yields a self-diffusivity for liquid iron of 2.5×10?5 cm2 s?1, which corresponds to a viscosity of 11 mPa s, in reasonable agreement with previous, theoretical, estimates. |