Synergistic Optimization of Electrical-Thermal-Mechanical Properties of the In-Filled CoSb Material by Introducing BiSbTe Nanoparticles.

How to realize the synergistic optimization of electrical-thermal-mechanical properties of thermoelectric materials is a key challenge. Using the BiSbTe nanoparticle as a mixed agent provides an effective way to address this challenge. Here, BiSbTe/InCoSb nanocomposites with different contents of BiSbTe nanoparticles were successfully prepared by ultrasonic dispersion combined with spark plasma sintering. Phase and microstructure characterization presented that Te nanoparticles were precipitated from BiSbTe during the SPS sintering process. Transport measurement results showed that the electrical conductivity was increased due to the increased carrier concentration induced by the charge transfer between Te nanoparticles and the matrix. The Seebeck coefficient was also increased due to the selected electron scattering and increased scattering factor. The lattice thermal conductivity was dramatically suppressed because of the enhanced phonon scattering induced by the BiSbTe nanoparticles and in situ-precipitated Te nanoparticles and increased dislocations. As a result, a higher average value of 1 was obtained in the range of 300-700 K by the decoupling of the electrical and thermal transport properties for the nanocomposite with 0.1 wt % of BiSbTe nanometer suspension. Furthermore, the flexural strength, fracture toughness, and hardness of the nanocomposites were also improved significantly. This work demonstrates that using the BiSbTe nanoparticle as a mixed agent can realize the synergistic optimization of electrical-thermal-mechanical properties of the In-filled CoSb thermoelectric material.