Krakow W, Shaw T M
IBM T.J. Watson Research Center, Yorktown Heights, New York 10598.
J Electron Microsc Tech. 1988 Mar;8(3):273-84. doi: 10.1002/jemt.1060080306.
High-resolution transmission electron microscopes operating at 300 and 400 kV were used to investigate the crystallography and microstructure of the perovskitelike YBa2Cu3O7-x. In this paper, we evaluate the performance attainable with these microscopes both empirically and by computer modelling. Based upon the assumption that oxygen may be a key to superconductivity properties, we have also investigated the visibility of the oxygen sites as well as the heavier yttrium and barium ion positions and the lighter Cu atom positions. We propose a scheme for observing different twin orientations in these structures and hence the oxygen atom positions seen in projection for the [100] and [010]. Our observations of both thick and thin regions of Y-Ba-Cu-O materials are reported as well as the problems of adjusting microscope parameters and specimen alignment to obtain interpretable images. We also give a preliminary report on the effects of heat treatment as seen in high-resolution micrographs to assess disorder of the heavy atoms and oxygen vacancies.
使用工作电压为300千伏和400千伏的高分辨率透射电子显微镜来研究类钙钛矿YBa2Cu3O7-x的晶体学和微观结构。在本文中，我们通过实验和计算机模拟来评估这些显微镜所能达到的性能。基于氧可能是超导性能关键因素的假设，我们还研究了氧位点以及较重的钇和钡离子位置和较轻的铜原子位置的可见性。我们提出了一种观察这些结构中不同孪晶取向的方案，从而观察到沿[100]和[010]方向投影时的氧原子位置。我们报告了对Y-Ba-Cu-O材料厚区域和薄区域的观察结果，以及调整显微镜参数和样品对准以获得可解释图像的问题。我们还给出了关于高分辨率显微照片中热处理效果的初步报告，以评估重原子的无序度和氧空位。
