Phonon Scattering Mechanism in Thermoelectric Materials Revised via Resonant X-ray Dynamical Diffraction

TL;DR

This study uses advanced X-ray diffraction to analyze atomic vibrations in thermoelectric materials, revealing that the vibrational dynamics of filler-cage systems are key to optimizing their thermoelectric performance.

Contribution

It introduces a multi-wavelength X-ray dynamical diffraction method to resolve atomic vibrations in thermoelectric materials, providing new insights into their vibrational mechanisms.

Findings

Vibrational dynamics of filler-cage system are crucial for thermoelectric optimization.

Multi-wavelength X-ray diffraction effectively resolves atomic vibration amplitudes.

Whole filler-cage system vibrations drive thermoelectric property improvements.

Abstract

Engineering of thermoelectric materials requires an understanding of thermal conduction by lattice and electronic degrees of freedom. Filled skutterudites denote a large family of materials suitable for thermoelectric applications where reduced lattice thermal conduction attributed to localized low-frequency vibrations (rattling) of filler cations inside large cages of the structure. In this work, a multi-wavelength method of exploiting X-ray dynamical diffraction in single crystals of CeFe$_4$P$_{12}$ is presented and applied to resolve the atomic amplitudes of vibrations. The results suggest that the vibrational dynamics of the whole filler-cage system is the actual active mechanism behind the optimization of thermoelectric properties.