Synthesis, Evolution of Morphology, Transport Properties for Bi2Te3 Nanoplates

Bi2Te3 has an extensive application as thermoelectric materials. Here, large scale Bi2Te3 single-crystal hexagonal nanoplates(NPs) with size of 0.4-0.8 mu m were synthesized successfully by hydro-thermal method. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) were used to characterize the Bi2Te3 nanoplates, which confirm the single crystal quality and smooth surface morphology with large size. We discussed the morphology-evolution in detail the influence of various reaction factors which including: the reaction temperature, the reaction time, the surfactants of the polyvinyl pyrrolidone (PVP) and pH value. The synthesis method is not only green, but also shortens the reaction time and improves the reaction efficiency. The Bi2Te3 nanopowders were hot-pressed into solid state pellets through spark plasma sintering (SPS). The values of the electrical conductivity sigma were about 0.16 x 10(-5) Sm-1 and 0.22 x 10(-5) Sm-1 at room temperature and 530 K, respectively. The values of the Seebeck coefficient S were around -81 mu VK-1 and -118 mu VK-1 at room temperature and 530 K, respectively.