Understanding Phonon Scattering by Nano-Precipitates in Potassium-Doped Lead Chalcogenides

TL;DR

This study combines experimental and theoretical approaches to understand how nanoprecipitates in potassium-doped lead chalcogenides affect phonon scattering, revealing how precipitate size distribution influences thermal conductivity and thermoelectric efficiency.

Contribution

It introduces a comprehensive analysis linking precipitate size distribution to phonon scattering and thermal conductivity in doped lead chalcogenides, guiding thermoelectric material optimization.

Findings

Precipitate size distribution critically affects phonon scattering.

Tuning precipitate sizes can lower thermal conductivity below single-size limits.

A physical basis for predicting minimum achievable thermal conductivity.

Abstract

We present a comprehensive experimental and theoretical study of phonon scattering by nanoprecipitates in potassium-doped PbTe, PbSe and PbS. We highlight the role of the precipitate size distribution measured by microscopy, whose tuning allows for thermal conductivities lower than the limit achievable with a single size. The correlation between the size distribution and the contributions to thermal conductivity from phonons in different frequency ranges provides a physical basis to the experimentally measured thermal conductivities, and a criterion to estimate the lowest achievable thermal conductivity. The results have clear implications for efficiency enhancements in nanostructured bulk thermoelectrics.