Lattice thermal conductivity and spectral phonon scattering in FeVSb-based half-Heusler compounds

Alloying and grain refinement have been conducted to reduce the lattice thermal conductivity of FeVSb-based half-Heusler compounds. And the effects of point defect and boundary on phonon scattering are analyzed using the Callaway model. Point defect scattering and boundary scattering, respectively, cut out the high-frequency and low-frequency phonons. Consequently, most of the heat $({\sim}70{\%})$ is carried by phonons with mean free path (mfp) in the range of 1–80 nm and 0.6–30 nm at Debye temperature and 650 K, respectively, indicating that further reduction in lattice thermal conductivity should enhance the scattering of phonons with these characteristic mfp