High thermoelectric performance and low thermal conductivity in Cu2−yS1/3Se1/3Te1/3 liquid-like materials with nanoscale mosaic structures. (December 2017)

• Record Type: Journal Article
• Authors: Zhao, Kunpeng; Zhu, Chenxi; Qiu, Pengfei; Blichfeld, Anders B.; Eikeland, Espen; Ren, Dudi; Iversen, Bo B.; Xu, Fangfang; Shi, Xun; Chen, Lidong
• Is Part Of: Nano energy. Volume 42(2017:Dec.)
• Page Start: 43
• Page End: 50
• Publication Date: 2017-12
• Subjects: Thermoelectric -- Mosaic structure -- Solid solution -- Thermal conductivity -- Electrical conductivity; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2017.10.042
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: 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−y S1/3 Se1/3 Te1/3 solid solutions using Cu2 S, Cu2 Se, and Cu2 Te matrix compounds. They are solved in hexagonal structures with space group R 3 ̅ m 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 Cu1.98 S1/3 Se1/3 Te1/3 with a maximum zT of 1.9 at 1000 K. Graphical abstract: Highlights: Triple-component Cu2−y S1/3 Se1/3 Te1/3 solid solutions with nanoscale mosaic structures was successfully achieved. Exceptional low thermal conductivity is obtained throughout the whole temperature range. Remarkably high zT value of 1.9 is achieved in Cu1.98 S1/3 Se1/3 Te1/3 at 1000 K.