Enhancing thermoelectric performance of SnTe via nanostructuring particle size

SnTe, one lead-free analogue of PbTe, has been paid attention in thermoelectric community because it has the similar rock-salt crystal structure and electronic band structure . However, SnTe possesses a very high total thermal conductivity (∼10.0 W m −1  K −1  at room temperature) and a mediocre ZT (∼0.2 at 723 K). In this study, to reduce its thermal conductivity, we prepare SnTe samples by melting reaction followed by mechanical alloying and spark plasma sintering . We demonstrate that both total thermal conductivity and lattice thermal conductivity can be considerably reduced through reducing particle size from micro-scale to nano-scale via facially mechanical alloying method. Experimental results show that the total thermal conductivity at room temperature can be reduced from ∼10 W m −1  K −1 for SnTe ingot to ∼3Wm −1  K −1 for SnTe with mechanical alloying 25 h. Correspondingly, the lattice thermal conductivity at room temperature was reduced from ∼5Wm −1  K −1 to ∼2Wm −1  K −1 . Combination of reduced thermal conductivity and moderate power factor, average ZT ave can be increased by 33.3%, from 0.09 for SnTe ingot to 0.12 for SnTe with nano-grain size.