原位液体透射电镜芯片的研发及基于此技术的贵金属纳米晶生长和刻蚀研究

发布时间：2018-06-02 05:15

本文选题：贵金属纳米晶 + 原位液体电镜　；参考：《浙江大学》2015年硕士论文

【摘要】：贵金属纳米晶体具有与其体相材料不同的独特的光学、电学、磁学和和机械性能,近年来受到诸多研究小组的关注,未来有望应用于光学和电磁器件、催化、能源存贮和转化领域。这其中,贵金属纳米晶的生长行为和机理研究是实现尺寸、形貌和电子结构调控的关键基础问题。在过去二十年里,已经有许多不同形貌的纳米晶体被合成,如球形,立方体,立方八面体,八面体等等。然而,由于原位探测技术的缺乏,仍旧有很多问题尚未解决。这其中对于微观过程的观察和机理研究是非常重要和亟需的,需要诸多手段包括原位探测技术的引入,才能有更加深入的理解和认识。随着电子显微镜以及微加工技术的发展,原位液体显微成像,作为一种崭新的实验技术和表征平台,使得直接观察到纳米晶的形核、生长成为可能。这项技术现在已被应用到各种不同纳米晶材料体系的研究当中,能在很高的空间分辨率和时间分辨率下研究颗粒的生长、扩散等动态过程。论文的主要工作就是先研发这种技术所需要的液体透射电镜芯片,然后基于该技术研究纳米晶体在溶液环境中的生长、刻蚀等行为。具体如下：(1)基于微机电系统(MEMS),我们成功加工制备了两种液体芯片,一种是可以直接应用在我们的原位液体样品杆中,另外一种可以通过胶水密封的技术进行.两种芯片都拥有很大的市场化前景。(2)提出和发展了一种利用电子束产生气泡并调控其尺寸,进而有效降低液层厚度,大大提高电镜表征的空间分辨率和衬度的方法。在此基础上实现了二维钯枝晶的生长及其机理研究。利用原位动态分析,包括分形,生长速度等,表明在这个体系下,扩散限制的聚集以及直接的原子沉积是钯枝晶生长的主要原因。(3)利用原位液体电镜技术首次实时观察了贵金属纳米晶氧化刻蚀行为,描述了钯六面体的刻蚀动力学行为。通过比较单分布和团簇纳米晶溶解速率的不同,揭示了局域环境对刻蚀行为的影响。
[Abstract]:Noble metal nanocrystals have unique optical, electrical, magnetic and mechanical properties different from their bulk materials. In recent years, noble metal nanocrystals have attracted the attention of many research groups, and are expected to be used in optical and electromagnetic devices, catalysis in the future. Energy storage and conversion. Among them, the growth behavior and mechanism of noble metal nanocrystals are the key issues to realize the control of size, morphology and electronic structure. In the past two decades, many nanocrystals with different morphologies have been synthesized, such as spherical, cubic, cubic octahedron, octahedron and so on. However, due to the lack of in-situ detection technology, there are still many problems to be solved. It is very important and urgent to observe and study the mechanism of microscopic process. It needs a lot of methods including in situ detection technology to have a deeper understanding and understanding. With the development of electron microscope and microfabrication technology, in situ liquid microscopic imaging, as a new experimental technology and characterization platform, makes it possible to observe the nucleation and growth of nanocrystalline directly. This technique has been applied to the study of various nanocrystalline materials, and can be used to study the dynamic processes of particle growth and diffusion at high spatial and temporal resolution. The main work of this paper is to develop the liquid transmission electron microscope chip which is needed for this kind of technology, and then to study the growth and etching behavior of nanocrystalline in solution environment based on the technology. Based on the MEMS MEMS, we have successfully fabricated two liquid chips, one of which can be directly used in our in-situ liquid sample rod and the other one can be sealed by glue. Two kinds of chips have a great market prospect. (2) A method of using electron beam to produce bubble and adjust its size is proposed and developed, which can effectively reduce the thickness of liquid layer and greatly improve the spatial resolution and contrast of electron microscope characterization. On this basis, the growth and mechanism of 2D PD dendrite have been realized. In situ dynamic analysis, including fractal, growth rate and so on, shows that in this system, Diffusion limited aggregation and direct atomic deposition are the main reasons for the growth of palladium dendrite. The oxidation etching behavior of noble metal nanocrystals was first observed in real time by in situ liquid electron microscopy. The etching kinetics of palladium hexahedron was described. The influence of local environment on etching behavior was revealed by comparing the dissolution rates of nanocrystalline clusters and single distribution.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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