Sharma R, Weiss K
Center for Solid State Science, Arizona State University, Tempe 85287-1704, USA.
Microsc Res Tech. 1998 Aug 15;42(4):270-80. doi: 10.1002/(SICI)1097-0029(19980915)42:4<270::AID-JEMT6>3.0.CO;2-U.
A Philips (Eindhoven, The Netherlands) 430 (300 keV) high resolution transmission electron microscope has been modified for in situ study of gas-solid interactions at elevated temperatures. This microscope can be best described as a synthesis, processing, and characterization laboratory for nano-size materials. A differentially pumped environmental cell (E-cell), capable of handling up to 20 torr of gas pressure, is fitted in the objective lens pole-piece gap. Single-tilt or double-tilt heating holders can be used to heat the samples up to 1,300 degrees C and 850 degrees C, respectively. The system can handle any non-corrosive gases such as H2, O2, N2, NH3, CO, water vapor. Electron diffraction patterns are used to elucidate the reaction path and to identify stable and/or metastable phases formed. Time, temperature, and pressure resolved electron diffraction patterns can also be used to estimate the thermodynamical conditions for the onset of a reaction and the stability range of different phases observed during the process can also be determined. The high resolution imaging capabilities enable elucidation of the basic structural mechanisms involved at near atomic level. The TV rate camera/video recording system is used to measure the reaction rates (kinetics of the reaction). A post projector energy filter (Gatan Imaging Filter, GIF) is attached at the bottom of the microscope in order to filter the inelastic scattering from the gases/thick samples as well as to obtain energy filtered images (chemical maps). The GIF can also be used as a parallel electron energy loss spectrometer (PEELS) to obtain changes in the sample composition during the reactions. The changes in the near-edge structures of PEELS spectrum is used to monitor changes in bonding and/or chemical environment elements during reaction. The chemical maps obtained can also be used to identify preferred regions of gas reactions, e.g., grain boundaries or surfaces, etc. Various modifications of the microscope are described in detail, with suitable examples showing the performance.
一台飞利浦（荷兰埃因霍温）430型（300 keV）高分辨率透射电子显微镜已被改装用于高温下气固相互作用的原位研究。这台显微镜堪称一个用于纳米材料的合成、加工和表征的实验室。一个差动抽气环境舱（E舱）安装在物镜极靴间隙中，该环境舱能够承受高达20托的气体压力。单倾或双倾加热支架可分别用于将样品加热到1300摄氏度和850摄氏度。该系统可处理任何非腐蚀性气体，如氢气、氧气、氮气、氨气、一氧化碳、水蒸气。电子衍射图案用于阐明反应路径并识别形成的稳定和/或亚稳相。时间、温度和压力分辨电子衍射图案还可用于估计反应开始的热力学条件，并且还能确定在此过程中观察到的不同相的稳定性范围。高分辨率成像能力能够阐明近原子水平上涉及的基本结构机制。电视速率相机/视频记录系统用于测量反应速率（反应动力学）。在显微镜底部安装了一个后置投影仪能量过滤器（Gatan成像过滤器，GIF），以便过滤来自气体/厚样品的非弹性散射，以及获取能量过滤图像（化学图谱）。GIF还可用作平行电子能量损失谱仪（PEELS），以获取反应过程中样品成分的变化。PEELS谱近边结构的变化用于监测反应过程中键合和/或化学环境元素的变化。获得的化学图谱还可用于识别气体反应的优先区域，例如晶界或表面等。文中详细描述了显微镜的各种改装，并给出了合适的例子来说明其性能。
