High thermoelectric performance and low thermal conductivity in Cu2−yS1/3Se1/3Te1/3 liquid-like materials with nanoscale mosaic structures
High thermoelectric performance and low thermal conductivity in Cu2−yS1/3Se1/3Te1/3 liquid-like materials with nanoscale mosaic structures
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DOI：
10.1016/j.nanoen.2017.10.042
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发表时间：
2017-12
期刊：
影响因子：
17.6
通讯作者：
K. Zhao;Chenxi Zhu;P. Qiu;A. Blichfeld;E. Eikeland;D. Ren;B. Iversen;Fangfang Xu;Xun Shi
中科院分区：
文献类型：
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作者：
K. Zhao;Chenxi Zhu;P. Qiu;A. Blichfeld;E. Eikeland;D. Ren;B. Iversen;Fangfang Xu;Xun Shi
马赛克晶体微结构是热电材料中解耦和平衡热电传输特性的最佳策略之一。在此，我们使用Cu 2 S、Cu 2 Se 和Cu 2 Te 基体化合物成功地在三组分Cu 2− y S 1/3 Se 1/3 Te 1/3 固溶体中实现了所需的纳米级镶嵌结构。通过单晶结构求解和Rietveld精修，将它们求解为具有空间群R 3̅ m 的六方结构。电子背散射衍射测量表明，所有样品均为多晶化合物，晶粒尺寸在微米范围内。然而，透射电子显微镜研究表明，这些微米级颗粒是由各种 10-30 nm 镶嵌颗粒组成的准单晶。每个马赛克颗粒都是完美的晶体，但相对于其他颗粒倾斜或旋转了非常小的角度。在这种情况下，保持了优异的电传输，但在整个温度范围内实现了异常低的导热率，这归因于点缺陷、类液铜离子和镶嵌纳米颗粒的晶格应变或界面的组合声子散射。综合所有这些有利因素，Cu 1.98 S 1/3 Se 1/3 Te 1/3 实现了非常高的热电性能，在 1000 K 时最大 zT 为 1.9。
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 Cu 2− y S 1/3 Se 1/3 Te 1/3 solid solutions using Cu 2 S, Cu 2 Se, and Cu 2 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 Cu 1.98 S 1/3 Se 1/3 Te 1/3 with a maximum zT of 1.9 at 1000 K.