Lone-pair electrons induced anomalous enhancement of thermal transport in strained planar two-dimensional materials
Lone-pair electrons induced anomalous enhancement of thermal transport in strained planar two-dimensional materials
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DOI：
10.1016/j.nanoen.2018.05.040
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发表时间：
2018-08-01
期刊：
影响因子：
17.6
通讯作者：
Hu, Ming
中科院分区：
文献类型：
--
作者：
Qin, Guangzhao;Qin, Zhenzhen;Hu, Ming
应变工程因其灵活性和健壮性而成为连续调节热传递的最有前途和最有效的途径之一。然而，以前的研究主要集中在量化热导率(Kappa)是如何被应变调制的，而对于电子起源的基本理解还有待探索。在这篇文章中，我们建立了一幅超越传统三维系统的二维材料中孤对电子驱动强声子非谐性的微观图像。我们给出了一类平面单分子膜在双向拉伸应变作用下kappa意外增大一个数量级的可靠解释，这与石墨烯的应变诱导kappa降低形成鲜明对比，尽管它们的平面结构相似。Kappa对拉伸应变的反常正响应归因于孤对电子与相邻原子的成键电子之间的相互作用减弱，从而降低了声子非谐性，导致Kappa增大。我们的研究揭示了应变调制热输运的电子起源，这将对未来与能源纳米技术和应用相关的研究产生重大影响。
Strain engineering is one of the most promising and effective routes towards continuously tuning thermal transport due to the flexibility and robustness. However, previous studies mainly focused on quantifying how the thermal conductivity (kappa) is modulated by strain, while the fundamental understanding on the electronic origin has yet to be explored. In this paper, we establish a microscopic picture of the lone-pair electrons driving strong phonon anharmonicity in two-dimensional (2D) materials beyond the traditional three-dimensional (3D) systems. We provide solid explanation for the unexpectedly up to one order of magnitude enlarged kappa of a class of planar monolayers with bilateral tensile strain applied, which is in sharp contrast to the strain induced kappa reduction in graphene despite their similar planar structures. The anomalous positive response of kappa to tensile strain is attributed to the attenuated interaction between the lone-pair electrons and the bonding electrons of neighboring atoms, which reduces phonon anharmonicity and leads to the enlarged kappa. Our study uncovers the electronic origin of the strain modulated thermal transport, which would have great impact on future investigations related to energy nanotechnologies and applications.