Affiliation:
1. State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 P. R. China
2. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 P. R. China
3. School of Chemistry and Materials Science Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Hangzhou 310024 P. R. China
4. Beijing National Laboratory for Molecular Sciences Beijing 100190 P. R. China
5. School of Physical Science and Technology ShanghaiTech University Shanghai 201210 P. R. China
Abstract
AbstractAgCuSe‐based materials have attracted great attentions recently in thermoelectric (TE) field due to their extremely high electron mobility, ultralow lattice thermal conductivity, and abnormal “brittle‐ductile” transition at room temperature. However, although the investigation on the crystal structure of AgCuSe low‐temperature phase (named as β‐AgCuSe) was started more than half a century before, it is still in controversy yet, which greatly limits the understanding of its intriguing electrical, thermal, and mechanical performance. In this work, via adopting the advanced three‐dimensional electron diffraction technique, this study finds that the AgCuSe‐based materials crystalize in an incommensurately modulated structure with an orthorhombic Pmmn(0β1/2)s00 superspace group. The local lattice distortion in the incommensurately modulated structure has weak effects on the conduction band minimum due to the delocalized and isotropic feature of Ag 5s states, leading to high carrier mobility. Likewise, the inhomogeneous, weak, and anisotropic Ag‐Se bonds result in the high degree of anharmonicity and ultralow lattice thermal conductivity. Furthermore, alloying S in AgCuSe reinforces the interaction between the adjacent Ag‐Se layers, yielding the “brittle‐ductile” transition at room temperature. This work well interprets the structure–performance relationship of AgCuSe‐based materials and sheds light on the future investigation of this class of promising TE materials.
Funder
National Natural Science Foundation of China
Subject
Biomaterials,Biotechnology,General Materials Science,General Chemistry
Cited by
5 articles.
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