High thermoelectric performance and low thermal conductivity in Cu2−yS1/3Se1/3Te1/3 liquid-like materials with nanoscale mosaic structures

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  • Kunpeng Zhao, Shanghai Institute of Ceramics Chinese Academy of Sciences, Chinese Academy of Sciences
  • ,
  • Chenxi Zhu, Shanghai Institute of Ceramics Chinese Academy of Sciences, Chinese Academy of Sciences
  • ,
  • Pengfei Qiu, Shanghai Institute of Ceramics Chinese Academy of Sciences
  • ,
  • Anders B. Blichfeld, Department of Materials Science and Engineering, Norges teknisk-naturvitenskapelige universitet, Trondheim
  • ,
  • Espen Eikeland
  • Dudi Ren, Shanghai Institute of Ceramics Chinese Academy of Sciences
  • ,
  • Bo B. Iversen
  • Fangfang Xu, Shanghai Institute of Ceramics Chinese Academy of Sciences
  • ,
  • Xun Shi, Shanghai Institute of Ceramics Chinese Academy of Sciences
  • ,
  • Lidong Chen, Shanghai Institute of Ceramics Chinese Academy of Sciences

Mosaic-crystal microstructure is one of the optimal strategies for decoupling and balancing thermal and electrical transport properties in thermoelectric materials. Herein, we successfully achieve the desired nanoscale mosaic structures in triple-component Cu2−yS1/3Se1/3Te1/3 solid solutions using Cu2S, Cu2Se, and Cu2Te matrix compounds. They are solved in hexagonal structures with space group R3̅m by means of single crystal structural solution and Rietveld refinement. Electron backscatter diffraction measurements show that all the samples are polycrystalline compounds with the grain size in the range of micrometers. However, transmission electron microscopic study reveals that these microscale grains are quasi-single crystals consist of a variety of 10–30 nm mosaic grains. Each mosaic grain is a perfect crystal but titled or rotated with respect to others by a very small angle. In this case, excellent electrical transports are maintained but exceptional low thermal conductivity is achieved throughout the whole temperature range, which is attributed to the combined phonon scatterings by point defects, liquid-like copper ions, and lattice strains or interfaces of mosaic nanograins. Combining all these favorable factors, remarkably high thermoelectric performance is achieved in Cu1.98S1/3Se1/3Te1/3 with a maximum zT of 1.9 at 1000 K.

OriginalsprogEngelsk
TidsskriftNano Energy
Vol/bind42
Sider (fra-til)43-50
Antal sider8
ISSN2211-2855
DOI
StatusUdgivet - 1 dec. 2017

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