Recently, the research groups of Prof. Jiaqing He from Physics Department at SUSTech published research paper entitled “Understanding of the Extremely Low Thermal Conductivity in High Performance Polycrystalline SnSe through Potassium Doping”  on Advanced Fuctional Materials Online. 

SnSe thermoelectric materials are element abundant and environmentally friendly, which is a research hotspot in thermoelectric area. At the beginning of this year, one collaborate work of Prof. He was published on Science found that single crystalline SnSe has excellent thermoelectric performance. However, the synthesis of single crystals is time-consuming, and single crystals themselves are prone to cleave. In this work, p-type polycrystalline SnSe as well as K0.01Sn0.99Se were prepared by combining mechanical alloying (MA) and spark plasma sintering (SPS). After K doping, the absence of Sn oxides at grain boundaries and the presence of coherent nano-precipitates in the SnSe matrix contributes to an impressively low lattice thermal conductivity of ~0.20 Wm-1K-1 at 773 K which results in a record high ZT of ~1.1 at 773 K in polycrystalline SnSe.

Micro-structure analysis by TEM (Transmission Electron Microscopy) indicated that the disappearances of Sn oxides as well as the formation of nano precipitates within the grains drastically decreased the lattice thermal conductivity.

links: http://dx.doi.org/10.1002/adfm.201602652