Lattice dynamics and reduced thermal conductivity of filled skutterudites

摘要

The great reduction in thermal conductivity of skutterudites upon filling the``void'' sites with Rare Earth (RE) ions is key to their favorablethermoelectric properties but remains to be understood. Using lattice dynamicmodels based on first principles calculations, we address the most popularmicroscopic mechanism, reduction via rattling ions. The model withstandsinelastic neutron scattering and specific heat measurements, and refuteshypotheses of an anharmonic RE potential and of two distinct localized REvibrations of disparate frequencies. It does indicate a strong hybridizationbetween bare La vibrations and certain Sb-like phonon branches, suggestinganharmonic scattering by harmonic RE motions as an important mechanism forsuppression of heat conductivity.