氢吸附五边形石墨烯的磁性研究

发布时间：2018-07-28 18:43

【摘要】：近年来,磁性材料已经被广泛的应用于生产电子器件、机械制造、轨道交通以及我们日常生活的各个领域,成为高新技术产业的基础功能性材料。并且随着科技的进步,各种电子设备和电器元件将会朝着更小、更轻薄、功能涵盖比较全面等方向发展,因而对磁性材料的大小、自身性质优异性的要求也越来越高。为了适应高新技术的发展及新兴市场的需求,对于新型磁性材料的研究,特别是对纳米磁性材料的研究将成为磁性材料研究的重点内容之一。2015年,王前教授和他的团队通过计算机拟合的方法模拟出一种新型石墨烯结构,五边形石墨烯。由于它自身的机械稳定性、高强度、耐高温等性能,使它在某些领域中可能优于六边形石墨烯材料。纯净的六边形石墨烯材料对外不显磁性,但可以通过使六边形石墨烯结构吸附原子、制造空穴和拓扑缺陷等方式使其具有磁性。那么,对于五边形石墨烯结构我们参照同样的方法来尝试研究其磁学性质。本文中,首先我们用氢原子吸附在纯净的五边形石墨烯1×1、2×2、3×3和4×4晶胞结构上,并分别得到稳定的吸附结构。然后利用第一性原理和密度泛函理论的方法对这些氢吸附的五边形石墨烯结构进行了磁性计算。结果显示除了氢吸附五边形石墨烯1×1晶胞结构(即氢吸附五边形石墨烯1×1晶胞的无磁吸附结构)对外不显磁性外,其余氢吸附的五边形石墨烯结构对外均显磁性,磁矩都是0.557μB/cell。并且通过对氢吸附五边形石墨烯2×2、3×3和4×4晶胞结构的态密度曲线进行分析可知,其磁矩的主要来源都是五边形石墨烯结构中C2原子的p态电子。此外,通过提高氢吸附五边形石墨烯1×1晶胞结构中氢原子的吸附高度,发现得到的新的氢吸附五边形石墨烯1×1晶胞结构对外显示磁性(即氢吸附五边形石墨烯1×1晶胞的显磁吸附结构),并且磁矩大小为0.551μB/cell。通过对其态密度曲线进行分析发现氢吸附五边形石墨烯1×1晶胞的显磁吸附结构磁矩的主要来源也是五边形石墨烯结构中C2原子的p态电子。随后,我们分别对这五个结构的电荷密度分布进行了研究,发现当氢原子吸附在五边形石墨烯结构上时,五边形石墨烯中的电荷进行了重新分布,其中H原子和C1原子之间获得很多的电荷,而C2原子则相对获得的电荷较少。我们可以将氢吸附五边形石墨烯1×1晶胞的两个结构看作纳米磁性开关,当提高氢原子的吸附高度时,整个吸附结构就呈现磁性,当压低氢原子的吸附高度时,整个吸附结构对外不显磁性。并且氢吸附五边形石墨烯1×1晶胞的显磁吸附结构也可以称为氢吸附五边形石墨烯结构能产生较大磁矩的最小结构单元。最后,我们通过对氢吸附五边形石墨烯1×1晶胞的两个结构之间的过渡路径的计算可知两个结构之间相互转换只需要很少的能量便可完成,由此可见这个纳米磁性开关是可能实现的,并有望广泛地应用于航空航天以及军事等领域。
[Abstract]:In recent years, magnetic materials have been widely used in the production of electronic devices, mechanical manufacturing, rail transportation and all fields of our daily life, which have become the basic functional materials for high and new technology industries. And with the progress of science and technology, various electronic devices and electrical components will be smaller, lighter, and more comprehensive, and so on. In order to adapt to the development of high and new technology and the demand of new market, the research on new magnetic materials, especially the research on nano magnetic materials, will become one of the key contents of magnetic materials research in.2015 years, Professor Wang Qian and his The team simulated a new type of graphene structure, pentagonal graphene by computer fitting. Due to its mechanical stability, high strength, high temperature resistance and other properties, it may be better than hexagonal graphene in some fields. Pure hexagonal graphene material is not magnetic, but it can be made by hexagonal stone. In this paper, we use hydrogen atoms to adsorb the 1 x 1,2 * 2,3 x 3 and 4 * 4 cell structures of pure pentagonal graphene with hydrogen atoms. The stability of the adsorption structure. Then using the first principle and the density functional theory, the magnetic properties of the pentagonal graphene structures adsorbed by these hydrogen are calculated. The results show that the 1 x 1 crystal structure of the pentagonal graphene (i.e. the non magnetic adsorption structure of the hydrogen adsorbed the Pentagon 1 * 1 cell) is not magnetic, and the rest is not magnetic. The structure of the pentagonal graphene structure adsorbed by hydrogen is all magnetic, and the magnetic moment is 0.557 B/cell.. By analyzing the state density curve of the 2 x 2,3 x 3 and 4 x 4 crystal cell structure of pentagonal graphene, the main source of its magnetic moment is the P state electron of the C2 precursor in the pentagene structure. In addition, the hydrogen adsorption is increased by five. The adsorption height of hydrogen atoms in the 1 x 1 crystal cell structure of the edge graphene is found. The new hydrogen adsorption pentagonal graphene 1 x 1 cell structure shows magnetic properties (i.e. the magnetic adsorption structure of the hydrogen adsorbed the Pentagon 1 x 1 crystal cells), and the magnetic moment is 0.551 mu B/cell., and the hydrogen adsorption five is found by the analysis of its state density curve. The main source of the magnetic moment of the magnetic absorption structure of the 1 x 1 cell of the edge graphene is also the P state electron of the C2 atom in the pentagonal structure. Then, we have studied the charge density distribution of the five structures, and found that the charge in the pentagonal graphene is re - enacted when the hydrogen atom is adsorbed on the Pentagon structure. The distribution, in which the H atom and the C1 atom get a lot of charge, and the C2 atom is relatively less charged. We can treat the two structure of the Pentagon 1 x 1 crystal as a nano magnetic switch. When the adsorption height of the hydrogen atom is increased, the whole structure of the adsorption is magnetic, when the adsorption height of the hydrogen atom is lowered. At the time, the whole adsorption structure is not magnetic. And the magnetic adsorption structure of the hydrogen adsorbed the Pentagon 1 x 1 cell can also be called the minimum structure unit of the hydrogen adsorbed the pentagonal graphene structure to produce the larger magnetic moment. Finally, we pass the hydrogen adsorption between the two structures of the two structures of the Pentagon 1 * 1 cell. It can be seen that only a small amount of energy is needed for the conversion of the two structures. It is possible that this nano magnetic switch is possible, and is expected to be widely used in aerospace and military fields.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O482.5

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