金纳米线的结晶性和晶体学取向及场发射效应研究

发布时间：2018-11-25 13:35

【摘要】：由于电子元器件和机械微型化的巨大发展和推动,人们越来越重视对纳米材料结构的基础研究。当材料的尺寸降低到纳米尺寸(约100nm),由于量子尺寸效应,它们的各种物理化学性质甚至生物活性等都变得非常奇特。基于可控的材料制备、结构和特性研究,人们渴望能根据环境和性能需要,设计并剪裁出具有特殊功能的处于纳米尺度的新材料。这些具有独特性能的纳米材料,在信息、能源、化工、环境、医药、国防及社会安全领域都有着广泛的应用前景,同时也为物理,化学,生命等基础学科的研究与发展带来巨大的机遇。结晶性和晶体学取向是材料的两个很重要的结构特性,对它们的研究可以拓展贵金属等纳米材料的潜在应用。本文首先介绍了纳米材料的性质和应用,以及场发射的概念,接着简单介绍了纳米材料的制备方法和表征方法。最后主要讨论了沉积电压、温度、纳米线直径对纳米线结晶性和晶体学取向的影响。通过使用无氰的环保电解液,采用模板辅助的电化学沉积法制备出了结晶性和晶体学取向可控的金纳米线。并分析了沉积电压、沉积温度和纳米线直径对这两个结构特性的影响机制。并进一步研究了金纳米线阵列的场发射效应。本文研究发现:低的电压有助于单晶的生长,而温度对纳米线的结晶性有着双重影响,在单晶和多晶纳米线中扮演着不同的角色。在单晶生长过程中,温度场的存在促进了生长面上原子的扩散;多晶生长过程中,温度场的存在使生长速率显著提高,促进三维成核。电压的不同会导致纳米线择优取向的不同,这主要是高的电压引起H离子的吸附导致不同晶面的晶面能发生变化。具体表现为:高电压时具有[100]取向,低电压时具有[111]取向。在保持其他条件不变的情况下,不同直径的纳米线具有不同的择优取向,这个主要是不同直径的纳米线在生长的过程中,两种不同的界面所占的主导地位不同所引起的。具体表现为:小直径时,纳米线具有[111]取向,大直径时具有[100]取向。此外还发现,金纳米线阵列可以有效促进场发射,单晶纳米线顶部的脊状结构和非密排面的低功函数是可能的两个因素。
[Abstract]:Due to the great development and promotion of electronic components and mechanical miniaturization, more and more attention has been paid to the basic research of nanomaterials. When the size of materials is reduced to nanometer size (about 100nm), their physical and chemical properties and even biological activities become very strange due to the quantum size effect. Based on controllable preparation, structure and properties of materials, people are eager to design and cut new nanoscale materials with special functions according to the needs of environment and performance. These nanomaterials with unique properties have a wide range of applications in the fields of information, energy, chemicals, environment, medicine, national defense and social security, as well as in physics, chemistry, The research and development of life and other basic disciplines bring great opportunities. Crystallization and crystallographic orientation are two important structural properties of materials. Their research can expand the potential applications of nanomaterials such as precious metals. In this paper, the properties and applications of nanomaterials and the concept of field emission are introduced. Then, the preparation and characterization of nanomaterials are briefly introduced. Finally, the effects of deposition voltage, temperature and diameter of nanowires on the crystallinity and crystallographic orientation of nanowires are discussed. By using cyanide-free environmental electrolyte and template assisted electrochemical deposition, the crystal and crystallographic orientation of the nanowires were controlled. The influence mechanism of deposition voltage, deposition temperature and nanowire diameter on these two structural characteristics was analyzed. Furthermore, the field emission effect of the Jinnanian wire array is studied. It is found that low voltage contributes to the growth of single crystal, while temperature has a double effect on the crystallinity of nanowires and plays a different role in single crystal and polycrystalline nanowires. In the process of single crystal growth, the existence of temperature field promotes the diffusion of atoms on the growth surface, and in the process of polycrystalline growth, the temperature field increases the growth rate and promotes three-dimensional nucleation. The difference of voltage will lead to different preferred orientation of nanowires, which is mainly due to the adsorption of H ions by high voltage, which leads to the change of crystal energy of different faces. The results show that there are [100] orientation at high voltage and [111] orientation at low voltage. The preferred orientation of nanowires with different diameters is different when other conditions remain unchanged. This is mainly due to the different dominant position of two different interfaces in the growth process of nanowires with different diameters. The results show that the nanowires have [111] orientation at small diameters and [100] orientations at large diameters. It is also found that the gold nanowire array can effectively promote the field emission. The ridge structure at the top of the single crystal nanowires and the low power function of the non-compact surface are two possible factors.
【学位授予单位】：中国科学院研究生院（近代物理研究所）
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.123

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