High Yield Bi2Te3 Single Crystal Nanosheets with Uniform Morphology via a Solvothermal Synthesis

Hexagonal nanosheet of Bi2Te3 single crystals with uniform morphology were facilely synthesized through a high yield solvothermal route at low temperature (180 degrees C). X-ray diffraction, scanning electron microscope, transmission electron microscope, selected area electron diffraction, and high-resolution transmission electron microscope were employed to characterize the products. In this solvothermal process, ethylene glycol (EG) was used as both reducing agent and solvent to simplify the process. The reaction temperature and alkaline environment play important roles in the formation of Bi2Te3 single crystals, and the morphology of the products can be influenced by the added surfactants. Nanosheets with uniform morphology were obtained when polyvinyl pyrrolidone (PVP) was used as surfactant. Transport properties of hot pressed bulk samples formed by the as-prepared nanosheets were investigated. Thermal conductivity of the hot pressed nanosheets was greatly reduced by up to 60%, compared to the melt sample, with an enhancement of Seebeck coefficient and a decrease of electrical conductivity.