Investigating the Possibility of Invariance in Electrical Resistivity in Transition Metals along their Pressure Dependent Melting Boundary

English Abstract:

Understanding core cooling through heat conduction and modelling the geodynamo requires knowledge of the thermal and electrical conductivities of relevant liquid Fe alloys at high pressures. Fortunately, the electronic component of the thermal conductivity of metals, which dominates their conductive heat transport, can be calculated from the electrical conductivity using the Wiedemann-Franz law. Measurement of physical properties at core pressures and temperatures (P-T) are challenging which motivates an alternative approach. We take advantage of the fact that the interface between the solid inner core and the liquid outer core is on the high pressure melting boundary of the core constituents. Attempts to evaluate a theory that predicts the electrical resistivity of a metal is constant on its P-dependent melting boundary is on-going using a large volume press up to 5 GPa. The evaluation is being made on transition metals Cu, Zn and Ni which offer comparison of the roles played by filled and partially-filled 3d bands in the electrical resistivity. Using a four-wire resistivity method, experiments are being conducted to provide a possible way to access core conductivity values at low, relative to core, P and T. The aim is to apply electrical conductivity measurements on Fe at low P and T to the inner core boundary in order to study the thermal regime of the core.