Enhanced thermoelectric performance in pristine AgSbTe2 compound via rational design of Ag2Te formation

Abstract

AgSbTe₂ has garnered considerable attention in the thermoelectric community due to its excellent thermoelectric properties in the medium to low-temperature region. However, its electrical transport performance is significantly affected due to both the Ag₂Te secondary phase and intrinsic defects. Here, a two-step prepared strategy is employed to promote synergistic optimization between the concentration of Ag vacancies and the mass percentages of Ag₂Te nanoprecipitate, resulting in a significant improvement in carrier mobility from ∼192.89 to ∼375.71 cm² V⁻¹ s⁻¹ at 300 K. Additionally, the nanoprecipitates and dislocation introduced through the rational design of Ag₂Te formation leads to a remarkable reduction in thermal conductivity. A maximum figure of merit of ∼1.18 at 548 K and an average figure of merit of ∼0.94 at 300–633 K were obtained for QA-AgSbTe₂ (quenching temperature (Q) = 773 K, Annealing time (A) = 24 h), surpassing those of pristine AgSbTe₂ compound with pervasive Ag₂Te. This work reveals that the carrier and phonon transport performance of AgSbTe₂ can be effectively decoupled by the optimization of Ag vacancy concentration and introduction of dislocation via adjusting mass percentages of Ag₂Te nanoprecipitate.