Book

Description

Bi2Te3 and Bi2Te3-based nanostructure powders were synthesized through a two-step co-precipitation chemical route using Bi(NO3)3.5H2O, TeO2, and SeO2 in a chemical solution. This approach offers controlled growth of single-crystal nanostructures for TE applications. Notably, HNO3 is recommended as the preferred chemical for solution preparation. The nanostructure powders were synthesized using a process that involved varying concentrations of HNO3 and NaOH, with or without NaBH4. Optimal synthesis conditions were determined to be 2M HNO3, 3M NaOH, and NaBH4. To minimize oxidation, a computer-controlled stream of pure H2 gas was passed through the samples. The synthesized samples were then comprehensively characterized structurally, compositionally, and optically. This successful synthesis method employs a straightforward two-step co-precipitation chemical route in which the precursor is reduced by NaBH4 to produce fine particles. The experimental results revealed that the samples exhibited a nanocrystalline structure with an average crystalline size of approximately 70 nm. This method offers simplicity, reliability, lower risk, and cost-effectiveness when compared to alternative approaches. The process involves synthesizing these nanostructures using varying concentrations of HNO3 and NaOH, both with and without NaBH4. While KOH and other substances have been commonly used for their eco-friendly, cost-effective, and readily available attributes, HNO3 is suggested as an alternative for solution preparation. The recommended approach entails initially dissolving TeO2 powder in HNO3, adding Bi(NO3)3.5H2O at 80°C, ensuring complete dissolution with magnetic stirring, and completing the remaining steps to generate single-crystal nanostructures. By analyzing the review and experimental results of these nanostructures grown via a simple chemical solution route, optimization has been achieved, yielding TE materials of reasonably acceptable quality for device applications.