The pressure dependence of the electrical resistivity of Fe across the α-ϵ phase transition with implications for the heat flux in small planetary cores

The electrical resistivity of Fe alloys at high pressures is a crucial physical parameter for determining the thermal conductivity of and magnetic dynamo generation in planetary cores. Discrepancies exist in previous studies on the magnitude of resistivity change across the bcc (α) to hcp (ϵ) transition at ∼13 GPa at room temperature. To address this, two methods were applied to measure the electrical resistivity of Fe at ambient temperature as a function of pressure in the range 5–24 GPa with high data density in a 3000-ton multi-anvil press. Our measured resistivity through the α-ϵ phase transition shows a relative increase of 0.84–1.5, which aligns with mid- to low estimates from previous studies. A nadir of solid Fe thermal conductivity of 30–55 W/m/K at ambient temperature up to 24 GPa is found by the Wiedemann-Franz Law, with implications for greater heat flux in small terrestrial planetary cores by the Bloch-Grüneisen Equation.