石墨烯吸附、掺杂铝原子的第一性原理研究

发布时间：2018-06-18 16:59

本文选题：第一性原理 + 铝　；参考：《中北大学》2017年硕士论文

【摘要】：传统的铝基复合材料由于其重量轻、高比强度和比刚度、热膨胀系数较低、易于加工等一系列优良的性能,被广泛应用于民用和军用领域。然而,普通的铝合金材料已经不能满足现代工业高速发展的需求。为了得到更佳的具有综合性能的铝基复合材料,寻求更合适的增强相是提高其性能的研究重点。石墨烯因具有许多优良的物理和化学性质而将它作为铝基复合材料的增强相,能够有效地提高铝合金的强度、弹性模量等性能。本文基于密度泛函理论的第一性原理计算研究了铝原子吸附于本征石墨烯以及掺杂石墨烯的电子结构及其相关性质。利用Material Studio软件中的CASTEP模块儿系统地研究了Al原子在本征石墨烯不同吸附位吸附、不同数目的Al原子吸附于石墨烯穴位以及Al原子吸附于四种掺杂石墨烯体系的吸附结构。本文主要计算了其电子结构、能量、态密度、能带以及电荷转移情况等共六章内容。第一章主要介绍了目前铝基复合材料、石墨烯增强铝基复合材料的国内外研究现状以及目前实验中石墨烯增强金属基复合材料的一些制备办法。第二章主要简单介绍了本文所用到的基于密度泛函理论的第一性原理的发展过程、原理。其中,密度泛函理论是主要包括Thomas-Fermi模型,Hoenberg-Kohn定理和Kohn-Sham方程。同时还简单介绍了我们计算所采用的模拟软件Material Studio中的Castep程序包。第三章我们运用第二章所提到的方法计算了单/双铝原子吸附位置不同对石墨烯电子结构性能的影响,发现单原子吸附最优的位置为穴位,双原子最优的吸附位置为间位。同时双原子吸附石墨烯比单原子吸附石墨烯结构更为稳定。第四章是在第三章的基础上进行的,由于双原子吸附比单原子吸附结构更为稳定,考虑随着吸附铝原子数的增多,石墨烯结构的变化。结果发现,随着覆盖度(即吸附Al原子数)的增加,其石墨烯吸附体系越来越稳定。同时铝原子的吸附属于物理吸附。第五章计算了铝原子吸附于掺杂石墨烯(掺杂原子:B、N、O、P)表面其电子结构性能的变化。结果表明铝原子吸附于氧/磷-石墨烯体系,对石墨烯结构的破坏较大。其成键电荷主要从铝原子的轨道上转移,并且从差分电荷密度分布图上看差分电荷分布比较局域,主要集中在铝原子和掺杂原子之间的电子轨道上。第六章是对本文工作的总结以及对未来工作的展望。
[Abstract]:Traditional aluminum matrix composites are widely used in civil and military fields because of their light weight, high specific strength and specific stiffness, low thermal expansion coefficient and easy processing. However, the common aluminum alloy can not meet the needs of the rapid development of modern industry. In order to obtain better aluminum matrix composites with comprehensive properties, it is important to seek more suitable reinforcement phase for improving the properties of aluminum matrix composites. Because of its many excellent physical and chemical properties, graphene can be used as the reinforcing phase of aluminum matrix composites, which can effectively improve the strength, elastic modulus and other properties of aluminum alloy. Based on the first principle calculation of density functional theory, the electronic structure and related properties of aluminum atoms adsorbed on intrinsic graphene and doped graphene have been studied in this paper. The adsorption structures of Al atoms at different adsorption sites of graphene, different numbers of Al atoms adsorbed on graphene acupoints and Al atoms adsorbed on four kinds of doped graphene systems have been systematically studied by using the CASTEP module of material Studio software. In this paper, the electronic structure, energy, density of states, energy band and charge transfer are calculated. In the first chapter, the current research status of aluminum matrix composites, graphene reinforced aluminum matrix composites and some preparation methods of graphene reinforced metal matrix composites are introduced. In the second chapter, the development process and principle of the first principle based on density functional theory are introduced briefly. The density functional theory mainly includes the Thomas-Fermi model Hoenberg-Kohn theorem and Kohn-Sham equation. At the same time, we also briefly introduced the simulation software material Studio Castep package. In chapter 3, we use the method mentioned in chapter 2 to calculate the effect of different adsorption sites of single and double aluminum atoms on the electronic structure and properties of graphene. It is found that the best adsorption position of single atom is acupoint and the best adsorption position of diatom is interposition. At the same time, diatomic adsorption of graphene is more stable than monoatomic adsorption of graphene. The fourth chapter is based on the third chapter. Because the diatomic adsorption is more stable than the monatomic adsorption structure, the structure of graphene changes with the increase of the number of aluminum atoms adsorbed. The results show that the graphene adsorption system becomes more and more stable with the increase of coverage (I. E. the number of Al atoms adsorbed). At the same time, the adsorption of aluminum atoms belongs to physical adsorption. In chapter 5, the electronic structure and properties of aluminum atoms adsorbed on the surface of doped graphene are calculated. The results show that the structure of graphene is destroyed by the adsorption of aluminum atoms on the oxygen / phosphorus-graphene system. The bond charge is mainly transferred from the orbit of the aluminum atom, and the differential charge distribution is localized from the differential charge density distribution diagram, which is mainly concentrated in the electron orbit between the aluminum atom and the doped atom. The sixth chapter is a summary of the work of this paper and prospects for future work.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.71;TB333

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