Abstract
It is widely acknowledged that the microstructure can be effectively modulated by a nano-secondary phase and further reduce lattice thermal conductivity in thermoelectric materials. However, considering their grain growth in the annealing and sintering process, it is crucial to discover appropriate nanoparticles, which can simultaneously inhibit the thermal conductivity and improve the power factor. Herein, we report the synthesis of PbTe@C core@shell nanocubes and their incorporation in commercial Bi0.5Sb1.5Te3(BST) powders. Since the carbon shell serves as a diffusion barrier to inhibit the growth of PbTe grains in high temperature process, several nano-sized PbTe@C particles can be preserved and observed in the BST bulk material. Thus, the lattice thermal conductivity (κlat) in the resulting composites was effectively reduced in the whole temperature range studied, which can be attributed to the scattering of high-density grain boundaries and large amounts of nano-incorporations. Meanwhile, the electrical properties are also improved upon the incorporation of PbTe@C and a large power factor of 29 μW cm−1 K−2 in the resulting composites was obtained. Furthermore, the average figure of merit value (ZTave) of the BST/0.3 wt%PbTe@C composite was 37% higher than that of the pure BST sample. This work provides a facile and novel strategy toward improving the thermoelectric performance of commercial BST.
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