High-purity bismuth telluride (Bi₂Te₃) nanostructures have been synthesized by a chemical reduction method with two processes: (1) co-precipitation by NaBH₄ and (2) annealing under hydrazine vapor and nitrogen gas atmosphere at T = 300°C. Based on the use of nitric acid (HNO₃) in the preparation of precursor solutions from primary materials, two syntheses were designed to prepare the Bi₂Te₃ nanostructures. Then, the structural, optical, and thermoelectric properties and the surface morphology of the obtained nanoparticles from the two syntheses were investigated. The X-ray diffraction analysis results revealed the formation of Bi₂Te₃ nanostructures in both syntheses. The values of the crystallite size and micro-strains of the Bi₂Te₃ nanostructure were obtained from the average Williamson–Hall (Langford) analysis and Scherrer methods. Field-emission scanning electron microscopy micrographs of the Bi₂Te₃ nanostructures showed hexagonal nanocrystals with different nano-sizes. Energy dispersive x-ray spectroscopy analysis confirmed the formation of the Bi₂Te₃ compound and the high purity of the synthesized nanostructures. The Bi₂Te₃ nanostructure produced in the second synthesis (HNO₃-Bi&Te) had a higher Seebeck coefficient (56.3 \(\mu \mathrm{V}/\mathrm{K}\)) and lower resistance (9 \(\mathrm{k}{\Omega }\)). The amount of ZT in this optimal synthesis (HNO₃-Bi&Te) increased by 6.5 times. The results of the Seebeck experiment mostly showed p-type conductivity for the two syntheses. Fourier-transform infrared spectroscopy analysis showed very low absorption of the NH₂ group on the Bi₂Te₃ nanostructured surface. This study showed that annealing in the presence of hydrazine vapor has major influences on the formation of the bismuth telluride binary phase.

高纯度碲化铋 (Bi ₂ Te ₃ ) 纳米结构已通过化学还原法合成，有两个过程：(1) NaBH ₄共沉淀和 (2) 在T = 300°的肼蒸气和氮气气氛下退火C。基于在由初级材料制备前体溶液中使用硝酸 (HNO ₃ )，设计了两种合成方法来制备 Bi ₂ Te ₃纳米结构。然后，研究了从两种合成中获得的纳米颗粒的结构、光学和热电性能以及表面形貌。X射线衍射分析结果揭示了Bi ₂的形成两种合成中的Te ₃纳米结构。Bi ₂ Te ₃纳米结构的微晶尺寸和微应变的值通过平均威廉姆森-霍尔（Langford）分析和谢勒方法获得。Bi ₂ Te ₃纳米结构的场发射扫描电子显微镜显微照片显示出具有不同纳米尺寸的六边形纳米晶体。能量色散 X 射线光谱分析证实了 Bi ₂ Te ₃化合物的形成和合成的纳米结构的高纯度。在第二次合成中产生的 Bi ₂ Te ₃纳米结构（HNO ₃-Bi&Te) 具有较高的塞贝克系数（56.3 \(\mu \mathrm{V}/\mathrm{K}\)）和较低的电阻（9 \(\mathrm{k}{\Omega }\)）。该最佳合成（HNO ₃ -Bi&Te）中ZT的量增加了6.5倍。Seebeck 实验的结果主要显示了两种合成的p型电导率。傅里叶变换红外光谱分析表明，在Bi ₂ Te ₃纳米结构表面上NH ₂基团的吸收非常低。该研究表明，在肼蒸气存在下退火对碲化铋二元相的形成有重大影响。