Synergistic regulation of pore and grain by hot pressing for enhanced thermoelectric properties of Bi_0.35Sb_1.65Te₃

Over the years, Bi₂Te₃-based alloys have garnered considerable recognition as exceptional thermoelectric materials. Researchers have diligently pursued avenues to enhance the properties of these materials, with a primary focus on reducing thermal conductivity while maintaining optimal electrical performance. Nonetheless, achieving this delicate balance has proven to be a formidable challenge. In this study, we present a novel synergistic optimization approach that entails manipulating the grain refinement and porous structure of the material through precise adjustments in cooling rate and relief temperature during the direct current hot pressing process. By meticulously controlling these parameters, we successfully engineered a multiscale microstructure that effectively promotes phonon scattering. Simultaneously, we optimized carrier concentration. The outcomes of our investigation are truly remarkable, as we attained a peak zT value of approximately 1.23 at 325 K, accompanied by an outstanding average zTave of approximately 1.2 across the temperature range of 300–400 K in the 6.5% porosity-Bi_0.35Sb_1.65Te₃ sample. These findings underscore the efficacy of the multiple synergies employed in our study. Moreover, our research provides a solid foundation for further exploration of complex micro structure modification techniques.