Cost-Efficient Preparation and Enhanced Thermoelectric Performance of Bi0.48Sb1.52Te3 Bulk Materials with Micro- and Nanostructures

A cost-efficient method has been developed based on the combination of hydrothermal exfoliation and spark plasma sintering (SPS) to fabricate Bi0.48Sb1.52Te3 bulk material with multiscale microstructures composed of micro- and nanosized microstructures. The thermoelectric (TE) transport properties of the bulk material with multiscale microstructures were measured along the directions parallel (||) and perpendicular (aSyen) to the SPS pressing direction. It is confirmed that the anisotropy of the electrical conductivity (sigma) and thermal conductivity (kappa) was decreased by the transformation of the microstructure from a single microscale structure to multiscale microstructures. As compared with Bi0.48Sb1.52Te3 bulk material with single microscale microstructures, the kappa value of the Bi0.48Sb1.52Te3 bulk material with multiscale microstructures was significantly reduced, the sigma value was slightly decreased, while the alpha value was slightly increased. Thus, a maximum ZT value of 1.1 was achieved at 350 K along the direction perpendicular to the pressing direction, increased by 20%. The enhanced ZT value was mainly attributed to the significant decrease in kappa induced by the multiscale microstructures. This work offers a new approach to improve TE performance by multiscale microstructural engineering.