Realizing high thermoelectric performance through the synergistic control of intrinsic conduction and enhanced phonon scattering in Cu-doped Bi0.5Sb1.5Te3 alloys

Abstract

This study explores the use of water-atomization for the mass production of (BiSb)₂Te₃ powders (∼2Kg/min) with enhanced thermoelectric performance, aimed at large-scale commercial applications. For the first time, excess Cu (0.05 wt%) was incorporated into p-type Bi_0.5Sb_1.5Te₃ (BST) alloy using a novel low-impact energy (LIE) process with varying intervals. The BST powders exhibit irregular shapes and bulk crystallites with an R$\bar{3}$m rhombohedral structure. The reduction in grain size and the formation of Cu-rich regions at the BST matrix effectively enhanced the phonon scattering in LIE-Cu_0.05BST alloys. Consequently, the optimized LIE 6h-Cu_0.05BST exhibited a reduced lattice thermal conductivity of 0.6 W/m. K. at 400 K, along with an improved figure of merit (zT) of 1.2. Furthermore, the spark plasma heat treatment (SPHT) of SPHT-Cu_0.05BST enhanced electrical conductivity by creating textured grain orientations raising the maximum room-temperature power factor to 4.5$\times$10⁻³ W/m. K², achieving a peak zT of 1.29 at 400 K.