Thermal conductivity of iron and nickel during melting: Implication to Planetary liquid outer core

TL;DR

This study measures the thermal conductivity of iron and nickel at high pressures and temperatures during melting, providing insights into planetary core properties and the behavior of these metals under extreme conditions.

Contribution

It presents new high-pressure, high-temperature measurements of iron and nickel's thermal conductivity during melting, using laser heated diamond anvil cells and modeling, which enhances understanding of planetary core dynamics.

Findings

Thermal conductivity increases with pressure in both metals.

A sharp decrease in conductivity occurs during melting at specific pressures.

Results align with previous multi-anvil measurements and suggest loss of atomic order during melting.

Abstract

We report the measurements of the thermal conductivity ($\kappa$) of iron (Fe) and nickel (Ni) at high pressures and high temperatures. $\kappa$ values are estimated from the temperature measurements across the sample surface in a laser heated diamond anvil cell (LHDAC) and using the COMSOL software. Near-isothermal $\kappa$'s are observed to increase with pressure in both the metals due to the increase of density of the pressed metals. In both metals $\kappa$'s are observed to follow a sharp fall during melting at different pressure points and are consistence with the other multi-anvil measurements. Constant values of $\kappa$ in these metals during melting at different pressures reveal the loss of long range order, which creates independent movement of atomic metals. The melting temperature measured in these metals from the sudden drop of $\kappa$-values are in a good agreement with the other melting measurements in LHDAC. The results obtained in this study is expected to provide an insight to the studies on the planets Mercury and Mars and their interior.