High thermoelectric performance in Ag-doped Bi0.5Sb1.5Te3 nanocomposites synthesized via low-temperature liquid phase sintering

In recent years, low-temperature liquid phase sintering (LPS) has emerged as a cost-effectiveness method for designing thermoelectric nanocomposites with reduced lattice thermal conductivity. However, their electrical conductivity often remains suboptimal, limiting the overall figure of merit (ZT). In this study, x wt% Ag/ Bi 0.5 Sb 1.5 Te 3 (x x = 0,0.1,0.2,0.3,0.4) nanocomposites are prepared through low-temperature LPS method followed by subsequent annealing. Remarkably, a small amount of silver atoms was doped into the Bi 0.5 Sb 1.5 Te 3 matrix post-annealing, significantly increasing carrier concentration and improving electrical conductivity. Additionally, residual Ag atoms formed Ag2Te nanoprecipitates, and lattice defects (including grain boundaries, twin boundaries, dislocations, and lattice distortions) effectively reduced lattice thermal conductivity. The 0.3 wt % Ag/Bi0.5Sb1.5Te3 0.5 Sb 1.5 Te 3 sample achieved a maximum ZT value of 1.36 at 400 K, double that of the pure Bi 0.5 Sb 1.5 Te 3 sample, with an average ZT value of 1.17, among the highest reported. This work demonstrates significant potential for synthesizing high-performance thermoelectric materials via low-temperature LPS methods.