Ultralow thermal conductivity and enhanced thermoelectric properties of SnTe based alloys prepared by melt spinning technique

SnTe based materials have attracted considerable attention owing to their eco-friendly nature. Here, we employed a melt spinning method combined with spark plasma sintering (MS-SPS) technique to optimize the electrical and thermal transport performance of SnTe based alloys. Doping with Sb optimizes carrier concentration efficiently, leading to an enhanced Seebeck coefficient and power factor. Unlike the original phonon dispersion relation, the introduction of Sb heightens the phonon-phonon interaction and flattens the phonon dispersion, resulting in a significant decline in the phonon group velocity. Combined with the enhanced scattering from lattice distortion, nanoprecipitates and large amounts of grain boundaries, an ultralow lattice thermal conductivity of 0.57 Wm⁻¹K⁻¹ was obtained for Sn_0.91Sb_0.18Te_1.18 MS-SPS alloy. An improved ZT value of 0.95 can be realized, which is 2.2 times higher than that of pure SnTe alloy. The enhanced phonon scattering and reinforced phonon-phonon interaction give valuable access to develop high-performance SnTe based thermoelectric materials.