Growth and characterization of Bi2Te2.70Se0.30 nanostructured materials by using a cost-effective chemical solution route

Abstract

A chemical solution route was employed to successfully synthesize single-phase Bi2Te2.70Se0.30 nanostructured powders at room temperature, ensuring minimal contamination. The synthesized powders underwent a comprehensive analysis using a range of characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), ultraviolet-visible (UV) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, atomic-force microscopy (AFM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The temperature-dependent behaviors of electrical conductivity and the Seebeck coefficient were also explored. The findings revealed that the synthesized powders displayed consistent spherical morphology, with an average diameter of 68.42 nm. Additionally, they exhibited a band gap energy of 0.615 eV. This research highlights the significant improvement achieved by incorporating selenium into the Bi2Te2.70Se0.30 materials through this synthesis process. The EDAX analysis confirmed the stoichiometric atomic ratio of bismuth (Bi), tellurium (Te), and selenium (Se) elements. Furthermore, the TEM images revealed the presence of agglomeration within the powders, demonstrating a primary crystalline size characterized by relatively small dimensions. The emergence of a pronounced exothermic peak at around 650 K signaled the commencement of oxidation for the Bi2Te2.70Se0.30 material. In electrical measurement, a synergy was achieved between heightened electrical conductivity and a well-matched Seebeck coefficient, with the goal of enhancing energy conversion efficiency in TE applications. These findings demonstrate the potential of the synthesized powders for producing nanostructured thermoelectric (TE) materials with controlled grain sizes, which are essential for the fabrication of high-performance thermoelectric generators (TEGs).