Nanostructured Te‒SnTe eutectic composites with enhanced thermoelectric performance

The eutectic Te‒SnTe composites were successfully prepared via a melt spinning method combined with a spark plasma sintering technique. The differences in thermoelectric properties for alloys near the eutectic composition were investigated. These composites could benefit from both the higher electrical conductivity of the SnTe phase and the superior Seebeck coefficient of the Te phase. The eutectic Sn-90at%Te composite exhibits an enhanced thermoelectric performance. Its maximum ZT is 1.8–2.1 times higher than that of pristine SnTe and Te materials. Upon doping with the Sb element, the electrical transport behavior could be further improved. Large amounts of grain boundaries and phase interfaces can readily scatter phonons. Combined with the extra scattering from nanoprecipitates, dislocations, and strain fields, an ultralow lattice thermal conductivity of 0.49 W m⁻¹ K⁻¹ could be obtained for the Sn-90at%Te-2.0at%Sb alloy at 633 K. The improved thermoelectric properties for the Te‒SnTe eutectic system provide a new strategy to explore high-performance materials.