Enhanced thermoelectric performance of Bi0.3Sb1.7Te3 based alloys by dispersing TiC ceramic nanoparticles

Bismuth antimony telluride (BiSbTe) composites are the most studied thermoelectric materials around room temperature. However, the extension of commercial applications is mostly restricted by its inferior conversion efficiency and mechanical stability. In this work, we report that the introduction of nano-sized ceramic titanium carbide (nano-TiC) can achieve a high dimensionless figure of merit ( ZT ) value up to 1.3 at 400 K and an increment in hardness over 37.93% at room temperature in Bi 0.3 Sb 1.7 Te 3 (BST) composites. On one hand, nano-TiC creates BST/TiC interfaces so that total thermal conductivity is reduced. Meanwhile, the Seebeck coefficient increases due to the scattering of carriers through the TiC-driven energy filtering effect. On the other hand, the hardness increases substantially with the addition of TiC resulted from the pinning effect induced hardening by grain boundaries and secondary phases. The results indicate that nano-TiC dispersion into BST matrix is effective for the enhancement in both thermoelectric performance and mechanical properties, which is favorable to practical applications. Moreover, the method of introducing nano-sized ceramic materials can also be extended to other thermoelectric systems.