纳米薄膜及其过渡金属插层化合物的电子性质

发布时间：2018-06-06 08:30

本文选题：二维材料 + 电子结构　；参考：《湘潭大学》2015年硕士论文

【摘要】：二维纳米材料具有很多特别的性质,例如石墨烯优良的载流子迁移率和机械性能、硒化铁的超导电性等。二维纳米材料的结构多种多样,例如六边形的二硫化钼、五边形的石墨烯、四边形的T型石墨烯、三边形的硅化二铜等,它们的电子结构也各不相同,从半导体到半金属到金属。人们研究发现把二维材料堆成三维材料,并在层间插入原子或分子构成层间化合物,可以获得独特的性质,例如六碳化钙的超导电性、碳泡沫石墨烯优良的光学性质等。特别的,层间化合物中还存在三维的半金属材料。这些优异的性质具有极高的应用价值,因而引起了人们广泛关注。论文共分五章。第一章,我们首先介绍了二维材料优良的性质,例如石墨烯的线性色散关系、硒化铁的超导电性,然后介绍了不同结构二维纳米材料的电子性质,如二硫化钼、五边形的石墨烯等。接着介绍了一些三维材料的研究情况,例如基于石墨烯的碳泡沫结构和石墨层间化合物六碳化钙的性质等。最后介绍了三维半金属材料的一些性质,例如铋化钠的三维Dirac点、砷化镉的超导电性等。第二章我们介绍了第一性原理理论计算方法。第三章我们研究了四边形二维碳化硅多样性的电子结构以及独特的边缘态。我们预测了三种四边形二维碳化硅结构,分别命名为T1、T2、T3。三种结构的碳、硅原子比例都是1:1,只有碳、硅原子的相对位置不一样。然而它们的电子结构却各不相同,分别是半导体(T1)、半金属(T2)和金属(T3)。这种多样性的电子结构来源于多样性的碳、硅键长。三种结构的条带的电子结构也十分独特。特别的,T1的条带具有独特的与平带有关边缘态。当我们对它进行电荷掺杂,由于电子之间的强关联相互作用,边缘态会劈裂,条带由半导体转变为半金属,相应的只有完全极化的电子才能沿着条带两条边沿中的一条变通过。第四章我们研究了石墨层间化合物MC6(M为过渡金属元素)中的三维Dirac point。石墨层间化合物是AA堆垛的石墨烯中烯插入过渡金属原子的三维材料。我们发现只有插入Ni族原子才能在垂直石墨烯平面的方向上得到三维Dirac point。这是由于碳原子的pz轨道与过渡金属原子的d轨道耦合产生的。同时我们发现,改变过渡金属原子的排列方式,Dirac point仍然存在。第五章是对我们两个研究工作的总结,同时一并对将来的研究工作进行了展望。
[Abstract]:The two-dimensional nanomaterials have many special properties, such as the excellent carrier mobility and mechanical properties of graphene, the superconductivity of iron selenide and so on. The structures of two-dimensional nanomaterials are varied, such as hexagonal molybdenum disulfide, pentagonal graphene, quadrilateral T-type graphene, triangular-shaped copper silicide and so on. From semiconductors to semi-metals to metals. It has been found that by stacking two-dimensional materials into three-dimensional materials and inserting atoms or molecules between layers to form interlaminar compounds, unique properties can be obtained, such as the superconductivity of calcium hexabarbonate and the excellent optical properties of carbon-foamed graphene. In particular, there are also three-dimensional semi-metallic materials in interlaminar compounds. These excellent properties have very high application value, so people pay more attention to them. The thesis is divided into five chapters. In chapter 1, we first introduce the excellent properties of two-dimensional materials, such as the linear dispersion relation of graphene, the superconductivity of iron selenide, and then introduce the electronic properties of two-dimensional nanomaterials with different structures, such as molybdenum disulfide. Pentagonal graphene, etc. Then some 3D materials are introduced, such as the carbon foam structure based on graphene and the properties of graphite interlaminar calcium hexabarbonate. Finally, some properties of three dimensional semimetallic materials are introduced, such as the three dimensional Dirac point of sodium bismuth, the superconductivity of cadmium arsenide and so on. In the second chapter, we introduce the calculation method of first principle theory. In chapter 3, we study the electronic structure and the unique edge state of quadrilateral two-dimensional silicon carbide. Three kinds of quadrilateral two-dimensional silicon carbide structures are predicted and named T1T2T3. The ratio of carbon to silicon is 1: 1 for each of the three structures, but the relative position of silicon is different. However, their electronic structures are different, they are semiconductors T _ (1), semimetallic (T _ (2) and metal (T _ (3). This diverse electronic structure is derived from the diversity of carbon and silicon bond lengths. The electronic structure of the three kinds of bands is also very unique. The special T 1 band has a unique edge state associated with the flat band. When we charge doped it, because of the strong correlation between electrons, the edge state will split, and the band will change from semiconductor to semi-metal, and only the fully polarized electrons can pass along one of the two edges of the strip. In chapter 4, we study the three dimensional Dirac pointof graphite interlaminar compound MC6(M as transition metal element. Graphite interlayer compounds are three-dimensional materials in which allene is inserted into transition metal atoms in graphene stacked by AA. We find that only by inserting Ni group atoms can three-dimensional Dirac point be obtained in the direction of the vertical graphene plane. This is due to the coupling of the PZ orbital of the carbon atom with the d orbital of the transition metal atom. At the same time, we find that point still exists by changing the arrangement of transition metal atoms. The fifth chapter is the summary of our two research work, at the same time, the future research work is prospected.
【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】：TB383.1;TB383.2

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