Preparation and Thermoelectric Properties of Bi2Te3 Fine-grained Bulk Materials

Bismuth and Tellurium nanoparticles were prepared by evaporation-condensation method in argon atmosphere, and n-type Bi2Te3 fine-grained thermoelectric bulk materials were fabricated by spark plasma sintering (SPS) at different temperatures from 663 to 723 K using mechanically alloyed (MA) powders. The phase compositions of powder and bulk samples were characterized by X-ray diffraction (XRD). The sizes and microscopic structures of nanoparticles and fractured cross section of the bulk samples were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. The thermoelectric transport properties were measured at 323 similar to 473 K. The results show that electrical transport properties are almost unchanged but thermal conductivity is reduced significantly from 1.93 W/m.K to 1.29 W/m.K at 423 K for the fine-grained bulks prepared by nanoparticles comparing with coarse-grained materials. The maximum ZT value after SPS at 693 K reaches 0.68 at 423 K.