Nanostructured thermoelectric Bi2Te3 powders were hydrothermally synthesized using various conditions to investigate the mechanism of powder formation. A homogeneous mixture in solution during the hydrothermal synthesis is critical to obtain a single phase of Bi2Te3. The growth of Bi2Te3 nanostructures can be categorized three stages: The synthesized powders are nanoparticles when the reaction temperature was below 100°C, regardless of the reaction time. As the reaction temperature is increased to 150°C, the Bi2Te3 products obtained show different morphologies depending upon the reaction time. Rod-like nanostructures with lower and higher aspect ratios are directly formed after 6 h and 12 h of reaction time, respectively. Further increasing the reaction time to 24 h at the same synthesis temperature results in the decomposition of the 1D nanostructures to nanoparticles. As a result, the anisotropic nanostructure is mainly controlled by the reaction temperature and time.
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