Experimental Determination of the Lorenz Number in Cu0.01Bi2Te2.7Se0.3 and Bi0.88Sb0.12

TL;DR

This paper introduces an experimental method to directly measure the electronic contribution to thermal conductivity in thermoelectric materials by using magnetic fields, enabling accurate determination of the Lorenz number.

Contribution

The study presents a novel experimental approach to directly measure electronic thermal conductivity contributions in thermoelectric materials, improving accuracy over traditional estimation methods.

Findings

Successfully measured electronic thermal conductivity contributions.

Determined the Lorenz number for specific thermoelectric compounds.

Enhanced understanding of thermal transport mechanisms in thermoelectrics.

Abstract

Nanostructuring has been shown to be an effective approach to reduce the lattice thermal conductivity and improve the thermoelectric figure of merit. Because the experimentally measured thermal conductivity includes contributions from both carriers and phonons, separating out the phonon contribution has been difficult and is mostly based on estimating the electronic contributions using the Wiedemann-Franz law. In this paper, an experimental method to directly measure electronic contributions to the thermal conductivity is presented and applied to Cu0.01Bi2Te2.7Se0.3, [Cu0.01Bi2Te2.7Se0.3]0.98Ni0.02, and Bi0.88Sb0.12. By measuring the thermal conductivity under magnetic field, electronic contributions to thermal conductivity can be extracted, leading to knowledge of the Lorenz number in thermoelectric materials.