Fabrication of bismuth telluride nanoparticles using a chemical synthetic process and their thermoelectric evaluations

Bismuth telluride nanoparticles for thermoelectric applications were successfully prepared via a water-based chemical reaction. In this process, we used both a complexing agent (ethylenediaminetetraacetic acid) and a reducing agent (ascorbic acid) to stabilize the bismuth precursor (Bi(NO₃)₃) in water and to favor the reaction with the reduced source of tellurium. The resulting powder was confirmed to range in size below ca. 100nm with the crystalline structure corresponding to the rhmobohedral Bi₂Te₃. We sintered the nanocrystalline powder via a spark plasma sintering process, thus we obtained the sintered body composed of nano-sized grains. Then, we measured some important transport properties (electrical resistivity, Seebeck coefficient, and thermal conductivity) of the sintered body to calculate its thermoelectric performance, the figure of merit. Finally, we discussed the effect of the nanostructure in the sintered body on the thermal conductivity.