Role of force-constant difference in phonon scattering by nano-precipitates in PbTe

TL;DR

This study investigates how nanoscale precipitates affect phonon scattering in PbTe, revealing that changes in force constants significantly influence thermal conductivity and could lead to more effective thermoelectric materials.

Contribution

The paper introduces the importance of force-constant differences in phonon scattering by nano-precipitates, refining predictions of optimal precipitate size for thermal conductivity reduction.

Findings

Force-constant differences enhance phonon scattering.

Optimal precipitate size is smaller when including force-constant effects.

Phonon scattering by precipitates may be stronger than previously estimated.

Abstract

We study the effect of nanoscale precipitates on lattice thermal conduction in thermoelectric PbTe using a combination of ab-initio phonon calculations and molecular dynamics. We take into account the effects of mass difference and change in force constants, and find an enhanced influence of the latter with increased precipitate concentration. As a consequence, our inclusion of the change in force constants in the calculation affords a smaller predicted optimal nano-precipitate size that minimizes the thermal conductivity. These results suggest that the phonon scattering by nanoprecipitates in thermoelectric composites could be stronger than previously thought.