材料科学
热导率
格子(音乐)
凝聚态物理
复合材料
物理
声学
作者
Ni Ma,Бо Лю,Rongchang Wu,Juping Xu,Wen Yin,Kai Li,Wei Bai,Jiong Yang,Chong Xiao,Yi Xie
摘要
Abstract The lattice thermal conductivity (κl) evokes immense interest not only in basic science but also in energy conversion applications. However, the low-κl crystalline materials are generally considered obtainable only from heavy elements, which usually implies poor stability and possible toxicity. Thus, it is crucial to thoroughly explore the low-κl materials composed of lighter elements. Here, we propose that light elements with a small discrepancy of atomic mass and radius, along with the hierarchical structure in the simple square-net lattice, can lead to low κl. The hierarchical structure depicts not only various chemical bonding but also the asymmetric geometry of building units, leading to the flat phonon branches and strong phonon-phonon interaction similar to that of heavy elements compounds. This realizes a giant phonon anharmonicity, which is the prerequisite for achieving extremely low κl. Taking KCu4Se3, as an example, our results reveal an extremely low κl of 0.12 W/m/K at 573 K, even lower than that of most heavy-element compounds. Our findings not only have the potential to reshape the fundamental understanding on thermal transport properties of matter but also broaden the horizons in the design of low-κl solids with light elements.
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