Strain field fluctuation effects on lattice thermal conductivity of ZrNiSn-based thermoelectric compounds

We present a model calculation of the lattice thermal conductivity of ZrNiSn-based half-Heusler thermoelectric compounds for temperatures where phonon scattering is dominated by Umklapp and point defect scattering. The difference in mass between impurity and host atoms dominates point defect scattering for alloying Hf on the Zr sublattice, whereas differences in size and interatomic coupling forces between impurity and host atoms dominate point defect scattering for alloying Pd on the Ni sublattice. Because Pt is heavier and larger than Pd, we predict that Pt will further reduce lattice thermal conductivity when alloyed on the Ni sublattice of these half-Heusler compounds.