Lattice dynamics and reduced thermal conductivity of filled skutterudites

Abstract

The great reduction in thermal conductivity of skutterudites upon filling the ``void'' sites with Rare Earth (RE) ions is key to their favorable thermoelectric properties but remains to be understood. Using lattice dynamic models based on first principles calculations, we address the most popular microscopic mechanism, reduction via rattling ions. The model withstands inelastic neutron scattering and specific heat measurements, and refutes hypotheses of an anharmonic RE potential and of two distinct localized RE vibrations of disparate frequencies. It does indicate a strong hybridization between bare La vibrations and certain Sb-like phonon branches, suggesting anharmonic scattering by harmonic RE motions as an important mechanism for suppression of heat conductivity.

modified version resubmitted to PRB. Results unchanged, text changed substantially

References in corpus (1)

• Glass-Like Heat Conduction in High-Mobility Crystalline Semiconductors

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• Intrinsic ultralow lattice thermal conductivity of the unfilled skutterudite FeSb${}_3$
• Electronic, vibrational and transport properties of pnictogen substituted ternary skutterudites
• Electronic Structure and Phase Stability of Yb-filled CoSb${}_3$ Skutterudite Thermoelectrics from First Principles
• Superconducting gap structure of the skutterudite LaPt4Ge12 probed by specific heat and thermal transport
• Energetic, structural and electronic features of Sn-, Ga-, O-based defect complexes in cubic In2O3
• Bidirectional Optimization onto Thermoelectric Performance via Hydrostatic-Pressure in Chalcopyrite AgXTe2 (X=In, Ga)
• Kagome modes, a new route to ultralow thermal conductivity?