石墨烯中弹性波的传播特性研究

This project will deal with the problem of wave propagation in graphene. Graphene, a single atomic layer of carbon, has a number of unique properties, which make them interesting for several different applications. In graphene, the carbon atoms are bonded together in a hexagonal pattern, and the bonds between carbon atoms hover halfway between single and double bonds. This unusual structure leads to typically important properties of graphene, such as high electronic quality, tunable band gap, and high elasticity. The carbon atoms of graphene are arranged as a special periodical structure. When acoustic or elastic waves propagate in these periodical structures, many surprising effects may arise, such as band gaps, wave localization. The main objectives of the present project are the development of modeling and calculation of elastic wave propagation in single-layer, bilayer and few-layer graphene based on molecular structure mechanics, considering the effects of defects, decorated surface or interface, and initial deformations. Through the approach of molecular structure mechanics, the features of elastic wave propagation in graphene will be illuminated. The primary goal of the present project is to gain a better understanding and a deeper insight into the dynamic behavior of graphene, which should be very helpful in the design of nano-devices based on this advanced and fascinating material.

作为碳晶体家族的新成员，石墨烯具有独特的单原子层二维晶体结构，是构建其他维度石墨材料的基本结构单元。石墨烯中碳原子呈六边形蜂窝状周期排列，特有的周期结构使其具有超高的载流子迁移率、高强度、能量禁带可调等性质。根据石墨烯与三维声子晶体结构的相似性，当弹性波在碳原子周期排列的石墨烯中传播时，会发生禁带通带、局部化、负反射等现象，即石墨烯可视为一类特殊的声子晶体，可以用来控制弹性波的传播。本项目将类比声子晶体，研究单层、两层及多层石墨烯中弹性波的传播问题，利用分子结构力学分析石墨烯的波动特性，考察石墨烯的带隙特征，并利用拉伸变形、缺陷、掺杂和修饰表界面等手段打破石墨烯的周期性，分析非初始状态石墨烯的动力特性，并研究弹性波的局域化等问题，深入探讨石墨烯的动力学特性，对石墨烯中弹性波的传播提供理论解释，为石墨烯在纳米声学、纳米减震降噪等器件的应用提供可靠地理论支持。

石墨烯由于其特殊的电子能带结构被认为是下一代纳米器件材料，在微机电系统(MEMS)和纳机电系统(NEMS)有着潜在的应用前景。石墨烯周期性蜂窝结构与三维声子晶体的结构具有相似性，当弹性波在单层、两层或多层石墨烯中传播时，会产生波的禁带与通带，并发生负折射、异常反射、声聚焦、局域化等现象。本项目拟采用分子结构力学对石墨烯中弹性波的传播问题进行研究，深入探讨石墨烯的动力学特性。.利用分子结构力学研究得到单层、两层及多层石墨烯在初始状态下的频散关系和本征模态，分析石墨烯层数和堆叠次序对弹性波频散关系的影响；计算分析有拉伸变形时石墨烯的禁带特性，考察碳碳共价键键长及键角的改变对石墨烯波动特性的影响，尝试通过利用变形达到石墨烯弹性波禁带可控的应用性要求；得到不同缺陷态时石墨烯禁带分布情况，利用不同的缺陷组合调节禁带特性；建立修饰表界面情况下石墨烯的分子结构力学模型，考察不同的修饰方式对石墨烯波动特性的影响；探讨分析石墨烯中由于缺陷等非理想因素的存在而引起的弹性波局域化问题。.通过对上述内容的研究，分析石墨烯的动力学特性及禁带调控机理，最终为石墨烯在振动控制、隔声减噪等相关纳米器件领域的应用提供理论基础。