Effective Scattering Cross-section in Lattice Thermal Conductivity Calculation with Differential Effective Medium Method

TL;DR

This paper improves the calculation of phonon scattering in heterogeneous thermoelectric materials by modifying the effective medium approach, validated through simulations and experiments, to better predict thermal conductivity reduction.

Contribution

It introduces a modified scattering cross-section and grain size dispersion into the Differential Effective Medium method for more accurate lattice thermal conductivity predictions.

Findings

Modified cross-section improves scattering estimates.

Validation against Monte-Carlo simulations and experiments.

Predictions for Full Heusler/Half Heusler systems.

Abstract

To further reduce the lattice thermal conductivity of thermoelectric materials, the technique of embedding nano-inclusions into bulk matrix materials, in addition to point defect scattering via alloying, was widely applied. Differential Effective Medium (DEM) method was employed to calculate two-phase heterogeneous systems. However, in most effective medium treatment, the interface scattering of matrix phonons by embedded nanoparticle was underestimated by adopting particle's projected area as scattering cross-section. Herein, modified cross-section calculations, as well as grain sizes dispersions, are applied in DEM, with the calculations then validated by comparing with Monte-Carlo simulations and existing experimental data. Predictions of lattice thermal conductivity reduction on in-situ formed Full Heusler(FH)/Half Heusler(HH) nano/matrix system are discussed.