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 ZTave can be increased by 33.3%, from 0.09 for SnTe ingot to 0.12 for SnTe with nano-grain size.