High homogeneity and ultralow lattice thermal conductivity in Se/Te-doped skutterudites obtained by self-propagating high-temperature synthesis and pulse plasma sintering

Abstract

Traditional ways to obtain homogeneous and efficient skutterudite-based thermoelectric materials usually require long processing time. In this study thermoelectric properties of Se and Te co-doped CoSb 3 bulk materials fabricated using a combination of self-propagating high-temperature synthesis and pulse-plasma sintering techniques were investigated. The proposed short-term fabrication route enabled synthesis of thermoelectric materials with high chemical homogeneity. Moreover, simultaneous doping with Se and Te beneficially influenced the electrical and thermal transport properties of the materials. As a result, an ultralow lattice thermal conductivity of 0.86 W m −1 K −1 has been attained while simultaneously doping and filling the voids in the skutterudite structure. The ultralow lattice thermal conductivity could be attributed to the unique lattice dynamics, enhanced point-defect, and electron-phonon scattering. Owing to these synergetic effects, a dimensionless figure of merit of 1.1 was obtained at 723 K. The findings show that combination of self-propagating high-temperature synthesis and pulse-plasma sintering techniques allow to fabricate chemically homogeneous and efficient thermoelectric materials as well as offer numerous advantages, such as time, energy efficiency, and potential scalability, to carry out large-scale production. • Se/Te modified skutterudites were fabricated via SHS-PPS route. • Seebeck potential mapping confirms high homogeneity of the fabricated materials. • The record low lattice thermal conductivity 0.86 W m −1 K −1 at 723 K was achieved. • Co 4 Sb 10.8 Te 0.6 Se 0.6 sample exhibits the maximum ZT of 1.1 at 723 K.