局域应变下石墨烯纳米结构的热输运性质研究

In recent years, strain engineering has become one of the most exciting topics in thermal transport research of graphene. However, the study on thermal transport of graphene nanostructures under nonuniform strain is seldom mentioned. In this project, the thermal transport behavior of graphene nanoribbon under local nonuniform strain will be investigated at atomic scale by using molecular dynamics simulations. We will also explore mechanisms of phonon transport in locally strained graphene nanoribbons, and find a method to tune thermal conductivity of graphene nanoribbons based on local stain effect, in order to open new avenues of research on improvement of thermoelectric performance for graphene nanostructures. The research findings can not only advance the basic research on the thermal transport in low-dimensional nanostructures, but also benefit the applications of the graphene-based thermoelectric devices.

近年来，应变工程成为石墨烯热输运研究领域的一个热点。但是，非均匀应变下石墨烯纳米结构的热输运现象还极少被研究。本课题基于分子动力学方法在原子尺度上研究局域的非均匀应变效应对石墨烯纳米带热输运的影响；探索石墨烯纳米带在局域应变下的声子热输运机制；寻找基于局域应变效应的石墨烯纳米带热导率调控方法，为石墨烯纳米结构热电性能提高开辟新的研究方向。研究成果不仅能够促进低维纳米结构热输运的基础研究，而且还将推动石墨烯基热电器件应用研究。

采用分子动力学方法，我们研究了石墨烯纳米带声子热导率的表面效应和表面/基底局域应变效应，研究了硅烯纳米带热导率的同位素掺杂效应。取得的结果主要有：(1) 烷基链长度和钝化密度对石墨烯纳米带声子热导率有重要影响，结构缺陷和表面局域应变增强了声子-缺陷的散射，导致体系声子热导率降低。(2) 表面/界面弱相互作用对石墨烯面内声子热导率有重要影响。(3) 硅烯纳米带的声子热导率表现出尺度效应和边界手性。同位素掺杂浓度、掺杂方式和掺杂原子排布对声子热输运有重要影响。我们的研究结果加深了二维材料纳米尺度下声子热输运的理解，提供了调控热导率的方法，有望应用于指导新型的纳米热电材料设计。