类石墨烯低维材料边缘修饰和表面吸附的第一性原理研究

发布时间：2017-12-31 07:05

本文关键词：类石墨烯低维材料边缘修饰和表面吸附的第一性原理研究　出处：《北方工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：低维纳米材料具有不同于传统块体材料的新颖的物理化学性质,使其在电子、光电子、电化学、气体传感器和生物等领域都有着非常高的应用前景。近年来,随着计算机处理性能飞跃式的进步以及计算理论的不断完善,采用理论模型和第一性原理计算方法对实验现象进行合理解释或预测纳米材料以及电子元器件的性能已逐渐成为主流。本论文系统地研究了边缘修饰对锯齿形BC_2N纳米带结构、电子结构、磁性性质的影响和蓝磷烯对气体分子的吸附性能以及气体传感特性,所采用的研究方法是基于密度泛函理论和非平衡格林函数的第一性原理计算方法。全文共分为五章:第一章中,介绍了低维纳米材料的性质、研究背景以及最新的科研进展,详细介绍了本论文中所研究的锯齿形BC_2N纳米带和蓝磷烯的结构特征、电磁性能、输运性能、实验制备以及可能的应用方向等相关的研究背景。第二章中,介绍了基于密度泛函理论和非平衡函数的第一原理计算方法及第一性原理计算软件。第三章中,我们采用H,F,Cl,OH,O,S和Se七种常见的非金属原子和分子对锯齿形BC_2N纳米带进行边缘修饰,系统地研究了不同的边缘修饰位置和条带宽度对BC_2N纳米带的结构、稳定性、电子结构和磁性性质的影响。研究结果表明:边缘状态和纳米带宽度对于一维纳米带材料的结构和电磁性质有较大程度的影响;使用不同原子或分子修饰后的纳米带呈现出不同的电磁特性,其中使用O原子修饰后的纳米带呈现出铁磁性的基态;增加纳米带宽度将会使整个体系的结合能负值均增大,稳定性增强;半导体性的纳米带的能隙大小随着宽度的增加而减少,当宽度足够大时,使用OH,F原子修饰后的纳米带和边缘裸露的纳米带的能隙逐渐消失,而使用H原子修饰的纳米带则表现出半极金属(half-metal)的特性。在第四章,我们选取七种气体分子(CO,CO_2,NO,NO_2,NH_3,SO_2和H_2S)作为吸附分子,研究了吸附后蓝磷烯的结构、稳定性、电磁性质和输运性能的变化。研究结果表明:选取的七种气体分子均是以物理吸附的形式吸附在蓝磷烯基体的表面;吸附气体分子后的蓝磷烯结构没有发生大的变形,说明吸附后的体系比较稳定。通过计算吸附后的基态和能带结构,我们发现吸附后的蓝磷烯依然保持着半导体的能隙,NO和NO_2分子吸附后体系呈现铁磁性的基态,磁矩为1.0μB。输运性能的计算中,我们发现吸附气体分子后蓝磷烯的输运电流发生了不同程度的改变,表现出较大的敏感度,这将为新型高性能的气体吸附传感器材料提供一种新的研究方向。在最后一章,对于本论文中的所做的研究工作进行了总结概括,并对后续的科研工作和方向进行了展望。
[Abstract]:Low-dimensional nanomaterials have novel physical and chemical properties different from those of traditional bulk materials, which make them have high application prospects in the fields of electronics, photoelectron, electrochemistry, gas sensors and biology. With the development of computer processing performance and the improvement of computing theory. The theoretical model and first-principle calculation method are used to explain or predict the experimental phenomena reasonably. The performance of nano-materials and electronic components has gradually become the mainstream. In this paper, the effect of edge modification on serrated B has been systematically studied. Structure of C2N nanobelts. The effects of electronic structure, magnetic properties, adsorption properties of blue phosphorus on gas molecules and gas sensing properties. The research method is based on the density functional theory and the first principle calculation method of non-equilibrium Green's function. The thesis is divided into five chapters: in chapter 1, the properties of low-dimensional nanomaterials are introduced. In this paper, the structure characteristics, electromagnetic properties and transport properties of serrated BC_2N nanobelts and blue-phosphorylenes are introduced in detail. In the second chapter, the first principle calculation method based on density functional theory and non-equilibrium function and the first principle calculation software are introduced. We used seven common nonmetallic atoms and molecules of BC_2N nanobelts, named Hedgehos and se, to modify the edge of the serrated BC_2N nanobelts. The structure and stability of BC_2N nanobelts with different edge modification positions and band width were studied systematically. The influence of electronic structure and magnetic properties. The results show that the edge state and the width of nanobelts have great influence on the structure and electromagnetic properties of one-dimensional nanobelts. The nanobelts modified by different atoms or molecules exhibit different electromagnetic properties, and the nanobelts modified by O atoms exhibit ferromagnetic ground state. Increasing the width of nanobelts will increase the negative binding energy and increase the stability of the whole system. The band gap of semiconductor nanobelts decreases with the increase of width. When the width is large enough, the gap of nanobelts modified with OHF atoms and those with bare edges gradually disappear. In Chapter 4th, we selected seven kinds of gas molecules, COCO2NOS-NOS2. As adsorption molecules, the structure and stability of cyanophosphorene after adsorption were studied. The results show that the selected seven kinds of gas molecules are physically adsorbed on the surface of blue phosphene matrix. The structure of the adsorbed gas molecule did not deform, which indicated that the adsorbed system was stable. The ground state and band structure of the adsorbed system were calculated. It is found that the adsorbed blue-phosphorylenes still maintain the band-gap no and the NO_2 molecule adsorbed with ferromagnetic ground state, and the magnetic moment is 1.0 渭 B. the transport properties of the system are calculated. We found that the transport current of blue-phosphorylenes changed in varying degrees after the adsorption of gas molecules, showing a greater sensitivity. This will provide a new research direction for the new high-performance gas adsorption sensor materials. In the last chapter, the research work done in this paper is summarized. The future research work and direction are prospected.
【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O647.3

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