Intensive Widmannstätten Nanoprecipitates Catalyze SnTe With State-of-the-Art Thermoelectric Performance

Abstract

Nanoprecipitates play a vital role in designing high-performance thermoelectric materials, particularly for those with short phonon mean-free paths. However, their effectiveness in reducing lattice thermal conductivity is hindered by the uncontrollable intensity, poor interfacial coherence, and suboptimal morphology. To address these limitations, AgPbSbTe₃ is used to alloy SnTe to form intensive Ag₂Te Widmannstätten nanoprecipitates for obtaining state-of-the-art thermoelectric performance. Advanced microscopy characterizations reveal the crystallographic orientation relationships between SnTe and Ag₂Te to guide the lath-shaped morphology of Ag₂Te, leading to the formation of the high-intensity Widmannstätten nanoprecipitates, which effectively scatter phonons to reduce the lattice thermal conductivity. Togethering the optimized electrical properties through carrier concentration adjustment, band convergence, and the energy filtering effect, a maximum figure of merit ZT of 1.5 at 723 K and an average ZT of 1.1 between 423 and 823 K is achieved in (SnTe)_0.80(Ag_1.05PbSb_0.95Te₃)_0.20, enabling a single-leg device and two-pair module with energy-conversion efficiency of 7.22% and 4.26% under a temperature difference of 450 K, respectively. The findings highlight the potential of intensive Widmannstätten nanoprecipitates as effective phonon scattering centers, providing a new pathway to enhance the thermoelectric performance of chalcogenides.