Multi-localization transport behaviour in bulk thermoelectric materials.

Wenyu Zhao,Hua Peng,Ping Wei,Jichao Li,Zhiyuan Liu,Jian Yu,Jihui Yang,Wanting Zhu,Qingjie Zhang,Dingguo Tang,Hongyu Zhou,Danqi He,Xin Mu,Xinfeng Tang,Chunlei Wang

doi:10.1038/ncomms7197

Abstract

Simultaneously optimizing electrical and thermal transport properties of bulk thermoelectric materials remains a key challenge due to the conflicting combination of material traits. Here, we have explored the electrical and thermal transport features of In-filled CoSb3 through X-ray absorption fine structure, X-ray photoemission spectra, transport measurement and theoretical calculation. The results provide evidence of three types of coexisting multi-localization transport behaviours in the material; these are heat-carrying phonon-localized resonant scattering, accelerated electron movement and increase in density of states near the Fermi level. The 5p-orbital hybridization between In and Sb is discovered in the In-filled CoSb3 compound, which results in a charge transfer from Sb to In and the enhancement of p–d orbital hybridization between Co and Sb. Our work demonstrates that the electrical and thermal properties of filled skutterudite bulk thermoelectric materials can be simultaneously optimized through the three types of coexisting multi-localization transport behaviours in an independent way.

Highlights

Optimizing electrical and thermal transport properties of bulk thermoelectric materials remains a key challenge due to the conflicting combination of material traits
We have explored the electrical and thermal transport features of In-filled CoSb3 through X-ray absorption fine structure (XAFS), X-ray photoemission spectra (XPS), transport measurement and theoretical calculation
We compare In Kedge X-ray absorption near-edge structure (XANES) experimental spectra of quenched In0.2Co4Sb12 (Q0.2) and annealed InxCo4Sb12 (x 1⁄4 0.1, 0.2 and 0.25) (Ax) with those of InSb and In metal (Fig. 1)

Summary

Introduction

Optimizing electrical and thermal transport properties of bulk thermoelectric materials remains a key challenge due to the conflicting combination of material traits. The results provide evidence of three types of coexisting multilocalization transport behaviours in the material; these are heat-carrying phonon-localized resonant scattering, accelerated electron movement and increase in density of states near the Fermi level. The 5p-orbital hybridization between In and Sb is discovered in the In-filled CoSb3 compound, which results in a charge transfer from Sb to In and the enhancement of p–d orbital hybridization between Co and Sb. Our work demonstrates that the electrical and thermal properties of filled skutterudite bulk thermoelectric materials can be simultaneously optimized through the three types of coexisting multi-localization transport behaviours in an independent way. Our data suggest that there are three types of coexisting multi-localization transport behaviours including heat-carrying phonon-localized resonant scattering, accelerated electron movement and increase in density of states (DOSs) near the Fermi level. Our work demonstrates that the electrical and thermal properties can be independently optimized through the three types of coexisting multi-localization transport behaviours

Methods

Results

Conclusion