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在材料科学和工业生产中,气态-固态相互作用是材料合成及处理过程中的基本环节之一,很多研究诸如纳米材料的生长、纳米材料对生态环境及生物组织的影响、催化剂的制备和催化过程,以及微量气体探测等都离不开对气态-固态反应的深入了解。随着纳米时代的来临,对气态-固态作用机制的研究也随之进入了原子分辨率的水平。所以样品室能够接受气体和根据需要对样品进行加热,并具备原子分辨率成像能力的透射电子显微镜就变得非常重要。本文旨在介绍应用日立300kVH-9500型高分辨透射电子显微镜对不同材料进行原位电子显微术观察的技术,目的是研究固体材料与气体相互作用而产生的原子水平上的结构变化。日立H-9500型电镜具有较为独特的真空系统设计。一台高速涡轮分子真空泵与样品室连接使得气体可以不断被注入样品室又不断被快速抽出。在样品室的上方加装有一个小孔光阑,其作用是让电子束正常通过但大幅减少样品室中的气体向高真空的电子枪区域的扩散。在电子枪的下方设有一个真空测量装置,当从样品室泄漏过来的气体过多时,电子枪下方的一个阀门会自动关闭从而保护电子枪不被损坏。这台电镜既可以作为普通电镜用于结构研究和成分分析,需要时又可以用日立公司的‘气体-加热样品台’将气体注入电镜样品室和对样品加热进行动态结构变化的高分辨研究。用这种电镜可以研究半导体材料、催化剂颗粒、纳米碳管、以及陶瓷材料。本文对部分研究结果进行了简略的介绍。
In the material science and industrial production, the gas-solid interaction is one of the basic steps in the synthesis and processing of materials. Many researches are concerned with the growth of nanomaterials, the influence of nanomaterials on the environment and biological tissues, the preparation and catalysis of catalysts Process, and trace gas detection can not do without a deep understanding of the gas-solid reaction. With the advent of the nano-age, the research on the mechanism of gas-solid interaction has also entered the atomic resolution level. Therefore, it is important for the sample cell to have a transmission electron microscope capable of receiving the gas and heating the sample as needed and having atomic resolution imaging capability. This article aims to introduce the technique of in situ electron microscopy using different Hitachi 300kVH-9500 high-resolution transmission electron microscopy to study the structural changes at the atomic level produced by the interaction of solid materials with gases. Hitachi H-9500-type electron microscope has a more unique vacuum system design. A high-speed turbomolecular vacuum pump is connected to the sample chamber so that gas can be continuously injected into the sample chamber and continuously extracted. A small aperture diaphragm is attached above the sample chamber to allow the electron beam to pass normally but to significantly reduce the diffusion of gas in the sample chamber to the high vacuum electron gun area. A vacuum measuring device is located under the electron gun. When there is too much gas leaking from the sample chamber, a valve under the gun automatically closes to protect the gun from damage. This electron microscope can be used as a common electron microscope for structural and compositional analysis. Hitachi gas-heated sample stages can be used to inject gases into electron microscope sample chambers and high-resolution studies of dynamic structural changes when needed. With this electron microscope can study semiconductor materials, catalyst particles, carbon nanotubes, and ceramic materials. This article briefly introduces some of the research results.