[SIT26-03] Advances in a high pressure-temperature experiment for understanding thermal transport property of the Earth’s core
Keywords:Core, Electrical resistivity, Thermal diffusivity
We have recently developed an internally resistive heated DAC technique to be capable of measuring the electrical conductivity of a metal sample via the four-terminal method . A new instrument to determine the thermal diffusivity of metal in-situ at high P-T has been made based on the combination of the thermoreflectance method and the LHDAC system . Such technical progress provided us chances to determine the thermal transport properties of core materials at the P-T conditions relevant to the Earth’s deep interior.
We report our new experimental results of the electrical resistivity measurements of liquid iron and Fe-Si alloys at high P-Tconditions using the four-terminal method in an internally heated DAC. The T dependence of electrical resistivity of hcp Fe-Si alloys was suppressed as both Si concentration and T increased, which indicates the resistivity saturation phenomenon: the electrical resistivity of metal asymptotically approaches the "saturation resistivity". The obtained saturation resistivities for hcpFe-Si alloys are comparable to those for hcp pure Fe at around 100 GPa. Resistivity increase in iron across melting was observed to 70 GPa. Besides, high-T thermal diffusivity of iron was obtained to Mbar pressure range utilizing the combination of the thermoreflectance method and LHDAC system. These new results shed light on the problem of the Earth’s core conductivity and thermal evolution.
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