Spherical Bi₂Te₃ Powder Synthesized by Oxide-Reduction Process via Ultrasonic Spray Pyrolysis

Bismuth telluride (<TEX>Bi₂Te₃</TEX>) and its alloys are well-known thermoelectric materials for ambient temperature applications. In this study, the dissolved Bi-Te precursor solution was used to synthesis metallic <TEX>Bi₂Te₃</TEX> powder via ultrasonic spray pyrolysis and reduction process. The droplets of the Bi-Te precursor solution were decomposed to Bi-Te oxide powders by ultrasonic spray pyrolysis. The spherical <TEX>Bi₂Te₃</TEX> powders were synthesized by reduction reaction in atmosphere of hydrogen gas at the temperature above <TEX>375∘C</TEX> for 6h. The reduced <TEX>Bi₂Te₃</TEX> powders have a mean particle size of <TEX>1.5μm</TEX>. The crystal structure of the powder was evaluated by X-Ray diffraction(XRD), and the microstructure with size and shape powders was observed by fieldemission scanning electron microscope(FE-SEM) and transmission electron microscope(TEM).