Significant reduction in lattice thermal conductivity in a p-type filled skutterudite due to strong electron–phonon interactions

Abstract

Electron–phonon interaction (EPI) has been widely suited in electrical transport properties. Nevertheless, its critical impact on the lattice thermal transport has been revealed in the last few years. Recently, people found that EPI can remarkably reduce the lattice thermal conductivity under a high carrier concentration and low temperature such as in silicon and two-dimensional materials; however, the discussions on thermoelectric (TE) materials are few. In this study, we investigate the EPI effect on the lattice thermal conductivities of skutterudites CoSb₃ and p-type filled BaFe₄Sb₁₂. At 300 K with 10²¹ cm⁻³ carrier concentration, the lattice thermal conductivity of CoSb₃ decreases from 10.7 W m⁻¹ K⁻¹ to 7.03 W m⁻¹ K⁻¹ (hole doping, reduction 34.3%) and 8.18 W m⁻¹ K⁻¹ (electron doping, reduction 23.6%), respectively, while that of BaFe₄Sb₁₂ decreases from 3.24 W m⁻¹ K⁻¹ to 1.14 W m⁻¹ K⁻¹ (5 × 10²¹ cm⁻³ for hole concentration) with a reduction of 64.8%. The significant EPI effect in BaFe₄Sb₁₂ is mainly due to the large density of states (DOS) and strong EPI strength. Our study reveals that EPI plays an important role in the lattice thermal conductivity of filled skutterudites, and it can further optimize their TE performances.