Thermoelectric properties of Bi0.4Sb1.6Te3-based composites with silicon nano-inclusions

Si/Bi 0.4 Sb 1.6 Te 3 bulk composites have been prepared by combining mechanical alloying with spark plasma sintering, and their thermoelectric properties have been investigated in the temperature ranges from 298 K to 498 K. The results indicate that with silicon content increasing, the thermopower ( S ) of the composite system increases substantially. Simultaneously, silicon nano-inclusions cause significant reduction in thermal conductivity ( κ ) owing to the decreased electrical conductivity and the enhanced phonon scattering of nanoparticles as well as phase boundaries. For the 0.5 vol% Si/Bi 0.4 Sb 1.6 Te 3 sample, S increases to 224.6 µV K −1 from 210.6 μV K −1 for the sample without silicon and κ decreases to 0.96 Wm −1 K −1 at 423 K from 1.07 Wm −1 K −1 for the sample without silicon, respectively. As a result, the highest ZT of 1.36 is obtained at 423 K of the 0.5 vol% Si/Bi 0.4 Sb 1.6 Te 3 sample.