Visualization of clay minerals at the atomic scale
Visualization of clay minerals at the atomic scale
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DOI：
10.1180/clm.2020.27
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发表时间：
2020-09
期刊：
影响因子：
1.5
通讯作者：
T. Kogure
中科院分区：
文献类型：
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作者：
T. Kogure
摘要本文表明，利用与构成层平行的主要带轴入射电子束对粘土矿物或层状硅酸盐进行高分辨率透射电子显微镜（HRTEM）成像，获得的图像中的对比度对应于单个阳离子柱，对于阐明这些矿物的神秘结构是必不可少的。层状硅酸盐中存在多型、无序和各种单位层或层间材料的互层现象。只有用HRTEM才能对这些变量进行局部和严格的测定，但要检验HRTEM图像从有限区域获得的结果是否代表整个标本，则需要使用其他技术，如x射线衍射。对粘土矿物的这些堆积特征的分析为了解它们的起源和/或形成过程提供了有价值的见解。最新的电子显微镜技术，包括非相干成像、~0.1 nm的高分辨率和使用新记录介质的低剂量成像，也将为我们了解粘土矿物的真实结构做出重大贡献。
Abstract This review demonstrates that high-resolution transmission electron microscopy (HRTEM) imaging of clay minerals or phyllosilicates with an incident electron beam along the major zone axes parallel to the constituting layers, in which the contrast corresponds to individual cation columns in the images obtained, is indispensable for elucidating the enigmatic structures of these minerals. Several kinds of variables for layer stacking, including polytypes, stacking disorder and the interstratification of various kinds of unit layers or interlayer materials, are common in phyllosilicates. Local and rigorous determination of such variables is possible only with HRTEM, although examination as to whether the results obtained by the HRTEM images from limited areas represent the whole specimen should be made using other techniques, such as X-ray diffraction. Analysis of these stacking features in clay minerals provides valuable insights into their origin and/or formation processes. Recent state-of-the-art techniques in electron microscopy, including incoherent imaging, superior resolutions of ~0.1 nm and low-dose imaging using new recording media, will also contribute significantly to our understanding of the true structures of clay minerals.