Validation of the Wiedemann-Franz Law in solid and molten tungsten above 2000 K through thermal conductivity measurements via steady state temperature differential radiometry

TL;DR

This study confirms that the Wiedemann-Franz Law accurately describes the electronic thermal conductivity of tungsten in both solid and molten states above 2000 K, validated through experimental measurements and simulations.

Contribution

The paper demonstrates the validity of the Wiedemann-Franz Law for molten tungsten at high temperatures using thermal conductivity measurements and ab initio simulations.

Findings

Wiedemann-Franz Law applies to molten tungsten above 2000 K.

Electronic thermal conductivity dominates over vibrational contributions at high temperatures.

Experimental and simulation results are in good agreement.

Abstract

We measure the thermal conductivity of solid and molten tungsten using Steady State Temperature Differential Radiometry. We demonstrate that the thermal conductivity can be well described by application of Wiedemann-Franz Law to electrical resistivity data, thus suggesting the validity of Wiedemann-Franz Law to capture the electronic thermal conductivity of metals in their molten phase. We further support this conclusion using ab initio molecular dynamics simulations with a machine-learned potential. Our results show that at these high temperatures, the vibrational contribution to thermal conductivity is negligible compared to the electronic component.