STUDYING OF OBTAINING CONDITIONS OF BISMUTH SELENIDE IN THE WATER

Abstract

This study investigates the conditions for synthesizing bismuth(III) selenide (Bi₂Se₃) from bismuth(III) oxide (Bi₂O₃) and elemental selenium in an aqueous medium using hydrazine monohydrate as a reducing agent. The effects of reagent quantity, reaction temperature, and reaction conditions on the formation and composition of the product were examined. The synthesis was performed by heating a mixture of bismuth(III) oxide, selenium powder, and diluted hydrazine monohydrate solution to the boiling point. The formation of a black precipitate indicated the production of bismuth selenide. The experimental results demonstrated that the amount of reducing agent significantly influenced the completeness of the reaction and the purity of the final product. Under suitable conditions, the obtained precipitate was identified as Bi₂Se₃. The synthesized material was characterized using chemical analysis, thermogravimetric analysis, differential thermal analysis, and X-ray phase analysis. The X-ray diffraction results confirmed the crystalline nature of the product and its correspondence to the reference diffraction pattern of Bi₂Se₃. Thermal analysis revealed changes in sample mass associated with oxidation and the subsequent volatilization of selenium oxide at elevated temperatures. The melting temperature was determined to be approximately 978 K, while the density measured by the pycnometric method was 6.78 g/cm³. The results demonstrate that bismuth(III) selenide can be obtained in an aqueous medium at relatively low temperatures. This approach may provide a useful alternative to high-temperature synthesis methods and contribute to the preparation of bismuth selenide for potential applications in semiconductor technology, thermoelectric devices, and thin-film production.