石墨烯和石墨炔纳米压痕力学性质的分子动力学研究

发布时间：2018-06-25 01:29

本文选题：石墨烯 + 石墨炔　；参考：《湘潭大学》2015年硕士论文

【摘要】：Sp2杂化形成的二维石墨烯是具有六角晶格结构的单原子层纳米材料,它有望成为突破基于硅纳米材料技术瓶颈的一种替代材料。石墨烯具有出色的光、电、磁和力学等方面的性质,在量子点、绝缘介质纳米隘口、自旋电子管、发光电化学电池、太阳能电池、半导体材料和纳米复合材料等领域有着广泛的应用前景。本文采用经典分子动力学理论方法,对石墨烯等二维纳米材料的纳米压痕力学性能展开了系统的研究,内容如下:(1)我们基于分子动力学方法研究了多层石墨烯的纳米压痕,采用分段拟合方法分别对大扰度和小扰度范围进行拟合分析杨氏模量。研究表明,石墨烯的杨氏模量对不同的应变范围具有不同的反应,取不同应变范围计算得到的值大小不一,小扰度范围得到的杨氏模量远大于大扰度范围。(2)我们模拟了多种不同尺寸圆膜和压头半径模型,研究了预应力对多层石墨烯的杨氏模量测量的影响。研究表明1-5层石墨烯杨氏模量约为1.00 TPa。当石墨烯厚度大于五个原子层,石墨烯的杨氏模量随着层数增大,这时它的杨氏模量与层数有一定关系。这种变化与石墨烯对应层数的预应力的变化自相一致。(3)我们分析了模拟温度和堆垛方式对石墨烯的杨氏模量测量的影响。在300 K至1000 K温度范围,石墨烯的杨氏模量与温度呈线性变化,杨氏模量随温度的升高而变大。这种现象是石墨烯强烈的非谐振性引起的。不同堆垛结构的多层石墨烯室温下测得的杨氏模量基本一致,堆垛方式对测量影响较小。(4)我们研究了单层缺陷石墨烯纳米压痕,分析了点、空位和Stone-Wales三种缺陷单层石墨烯的杨氏模量。研究了单层缺陷石墨烯的杨氏模和缺陷影响力学性能的机制,单层缺陷石墨烯的力学强度与缺陷的尺寸以及缺陷处的晶界角度有关。(5)我们开创性的利用分子动力学方法研究了新型二维纳米材料石墨炔的纳米压痕。结果表明石墨炔的力学强度约为石墨烯的1/2,石墨炔比石墨烯柔软,石墨炔对温度的反应更迟钝,阻抗更弱。
[Abstract]:Sp2 hybrid two-dimensional graphene is a monoatomic layer nanomaterial with hexagonal lattice structure, which is expected to be a substitute material to break through the bottleneck of silicon nanomaterials technology. Graphene has excellent optical, electrical, magnetic and mechanical properties, such as quantum dots, dielectric nanowires, spin tubes, electrochemically emitting cells, solar cells, etc. Semiconductor materials and nanocomposites have a wide range of applications. In this paper, the mechanical properties of nano-indentation of graphene and other two-dimensional nanomaterials are systematically studied by using classical molecular dynamics theory. The contents are as follows: (1) based on the molecular dynamics method, we have studied the nano-indentation of multilayer graphene. The section fitting method is used to fit and analyze the Young's modulus in the range of large disturbance and small disturbance respectively. The results show that the Young's modulus of graphene has different reactions to different strain ranges, and the values calculated from different strain ranges are different. The Young's modulus obtained in the small disturbance range is much larger than that in the large one. (2) We simulate a variety of models of circular film and head radius with different sizes and study the influence of prestress on the Young's modulus measurement of multilayer graphene. The results show that the Young's modulus of 1-5 layers of graphene is about 1.00 TPA. When the thickness of graphene is greater than five atomic layers, the Young's modulus of graphene increases with the number of layers. This change is consistent with the change of the number of graphene layers. (3) the effects of simulated temperature and stacking mode on the Young's modulus of graphene are analyzed. In the temperature range of 300K to 1000 K, the Young's modulus of graphene varies linearly with the temperature, and the Young's modulus increases with the increase of temperature. This phenomenon is caused by the strong non-resonance of graphene. The Young's modulus measured at room temperature for multilayer graphene with different stacking structures is basically the same. (4) the nanoindentation of graphene with single layer defects is studied and the points are analyzed. The Young's modulus of graphene monolayer with vacancy and Stone-Wales defects. The Young's model of graphene with monolayer defects and the mechanism of the effect of defects on mechanical properties were studied. The mechanical strength of graphene monolayer is related to the size of defects and the grain boundary angle of defects. (5) We have studied the nano-indentation of graphene by molecular dynamics. The results show that the mechanical strength of graphene is about 1 / 2 of that of graphene.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O613.71;TB383.1

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