A new Measurement of Thermal Conductivity of Iron at high pressures and temperatures

TL;DR

This study measures the thermal conductivity of iron at high pressures and temperatures relevant to Earth's core, revealing how it varies with pressure and phase changes, using laser-heated diamond anvil cell experiments.

Contribution

The paper provides new experimental data on iron's thermal conductivity up to 120 GPa, including phase-specific measurements and temperature dependence during melting.

Findings

Thermal conductivity of γ-Fe increases linearly up to 40 GPa.

Thermal conductivity of ε-Fe saturates around 52 W/m·K between 77-120 GPa.

Thermal conductivity drops sharply during melting, indicating liquid layer formation.

Abstract

Thermal conductivity of the most abundant element in the planetary core, Iron (Fe) is measured up to Earth's outer core pressure $\sim 120$ GPa. The measurements are carried out using the laser heated diamond anvil cell facility, where the absorbed power by Fe metal foil is calculated using thermodynamical equation. The thermal conductivity of $\gamma-Fe$ linearly increases up to a maximum experimental pressure 40 GPa. Thermal conductivity of $\epsilon-Fe$ measured by us shows a saturated value $\sim$ 52 ($\pm$ 5) $Wm^{-1}K^{-1}$ in the pressure range 77 - 120 GPa. At different pressures temperature dependence of thermal conductivity show a sharp drop during melting, which indicates the formation of liquid layer resulting in a thermal buffer to the heat conduction.