Electronic, vibrational and transport properties of pnictogen substituted ternary skutterudites

TL;DR

This study uses first principles calculations to analyze how pnictogen substitutions in ternary skutterudites affect their electronic, vibrational, and thermoelectric properties, highlighting the impact of bonding character and carrier concentration.

Contribution

It introduces a new Wannier function-based methodology for calculating electronic transport coefficients in ternary skutterudites, providing insights into substitution effects.

Findings

Transport coefficients are highly sensitive to carrier concentration.

Bond polarity negatively impacts thermoelectric performance.

Substitutions alter electronic and vibrational spectra significantly.

Abstract

First principles calculations are used to investigate electronic band structure and vibrational spectra of pnictogen substituted ternary skutterudites. We compare the results with the prototypical binary composition CoSb$_3$ to identify the effects of substitutions on the Sb site, and evaluate the potential of ternary skutterudites for thermoelectric applications. Electronic transport coefficients are computed within the Boltzmann transport formalism assuming a constant relaxation time, using a new methodology based on maximally localized Wannier function interpolation. Our results point to a large sensitivity of the electronic transport coefficients to carrier concentration and to scattering mechanisms associated with the enhanced polarity. The ionic character of the bonds is used to explain the detrimental effect on the thermoelectric properties.