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急冷Al-Mn,Al-Fe,Al-Cr和Ni-Ti-V合金中准晶体的发现[1-3]向我们提出了发展准晶体结构分析技术的研究课题.目前准晶体颗粒只有微米量级,高分辨电子显微术应是一种有前景的准晶体结构分析手段.可是,高分辨电子显微象的分辨率有限,难以从象上分辨开准晶体中的单个原子.而从分辨率 相似文献
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自从发现了高Tc超导氧化物以来,人们纷纷用各种方法研究它们的晶体结构.七十年代发展起来的高分辨电子显微术,给人们提供了直接观察晶体结构的手段.图1是超导转变温度为90K的Y-Ba-Cu-O化合物的高分辨电子显微象,是我们用JEM-200C X高分辨电子显微镜拍摄的.电子加速电压为200kV.Y-Ba-Cu-O化合物属正交晶系,晶胞参数a=0.389um,b=0.382nm,c=1.166nm.晶体沿c方向的周期均为a方向的三倍,具有类钙钛矿型超结构.图2给出了该晶体的结构模型. 图1所示的高分辨电子显微象是用楔状晶体拍摄的.图1的上端对应于楔状晶体的薄区,晶体厚度约为几个nm,… 相似文献
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借助高分辨电子显微像结合解卷处理的方法研究了GaN晶体中的堆垛层错.简要介绍了高分辨电子显微像的解卷处理原理,指出通过解卷处理可以把本来不直接反映待测晶体结构的高分辨电子显微像转换为直接反映晶体结构的图像.用高分辨电子显微像观察了GaN晶体中的堆垛层错,对高分辨电子显微像作了解卷处理.在解卷像上清晰可见缺陷核心的原子排列情况,据此确定了层错的类型.此外,还讨论了解卷处理在研究晶体缺陷中的效用.
关键词:
GaN
晶体缺陷
高分辨电子显微学
解卷处理 相似文献
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本文用Linfoot象质评价函数对弱相位物体成象高分辨电子显微镜的失焦特性作了研究。测量厚度为10nm的无定形非晶碳膜的高分辨电子显微象功率谱,从而确定相对结构容量分布,并从理论计算上进行了证实,据此对保真度相关量及未知晶体成象和自动聚焦作了讨论。
关键词: 相似文献
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一实验凝聚态物理学叶恒强、宁小光:材料表面的高分辨电子显微术近年来,由于电子光学技术、超高真空技术及与之相关的表面制备技术的迅速进展,各种能谱仪、质谱仪、衍射仪和显微象技术不断出现并日趋完善. 相似文献
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本文提出从高分辨电子显微像中,利用光学、全息和部分相干等方法,提取传递函数,制作相位和振幅滤波器,实现解卷,提高高分辨电子显微像的分辨率. 相似文献
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介绍了一种测定晶体结构的图像处理技术,它基于高分辨电子显微学与电子电子衍射的结合。中给出了其方法的示意图。 相似文献
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本文提出一个把高分辨电子显微图和相应的选区电子衍射图结合起来以测定晶体结构的方法。此法可解决从电子衍射数据求解结构振幅绝对值的问题,亦可解决各种衍射分析所共有的相角问题。所得结构图像的分辨本领将优于电子显微图,而有可能接近于衍射分辨极限。 相似文献
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Youdou Zheng Rong Zhang Yong Yan Duan Feng T. W. Kim B. D. McCombe 《Applied Physics A: Materials Science & Processing》1990,50(2):237-239
An Fe film was grown on an Si(100) substrate by metalorganic chemical vapor deposition (MOCVD) using thermal decomposition of iron pentacarbonyl, Fe(CO)5. The X-ray diffraction and cross-sectional high resolution electron microscopy (HREM) show that the Fe deposited film is a single crystal Fe film on Si(100). Single crystal Fe/Si Schottky barrier diodes exhibit good rectification. 相似文献
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从硅位错附近得到的会聚束电子衍射图样表明高阶劳厄带线和菊池线分裂,晶体学等效的衍射显示不同的分裂或不分裂,这些结果可以用晶体缺陷的衍衬理论来解释,不分裂的衍射相当于位错的不可见,即g·b=0,会聚束电子衍射提供了强有力的研究缺陷的高空间分辨率手段。
关键词: 相似文献
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介绍了利用高分辨电子显微不进行晶体结构分析的一种方法-轻原子成像法的建立过程及其在铜,镍,银等金属的初期氧化产物结构分析中的应用,介绍了利用轻原子成像法的思想解决厚膜上观察表面结构的可能性问题的新进展。 相似文献
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A technique has been developed for occluding biopolymer molecules in thin films of epitaxial gold. The method relies on deposition of the biopolymer from aqueous solution by “streaking” followed by continued ordered deposition of gold on the single crystal gold support film. The advantage of this technique of specimen preparation for electron microscopy are the high resolution (of the order of 0.5 nm) and excellent stability while under observation. Good contrast has been obtained reproducibly and is associated with the presence of the biopolymer as an occluded defect in the gold crystal. 相似文献
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Using a high resolution coincidence technique, we measured for the first time the angular and energy correlation of an electron pair emitted from the valence band of a single crystal upon the impact of an electron with a specified momentum. We observe a hole in the measured two-particle correlation function when the two excited electrons have comparable momentum vectors, a fact traced back to exchange and repulsion among the electrons. We find the hole is not isotropic, has a finite extension, and is strongly suppressed when decoherence is operating. 相似文献
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A high‐energy‐resolution resonant inelastic X‐ray scattering spectrometer at ID20 of the European Synchrotron Radiation Facility
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M. Moretti Sala K. Martel C. Henriquet A. Al Zein L. Simonelli Ch. J. Sahle H. Gonzalez M.-C. Lagier C. Ponchut S. Huotari R. Verbeni M. Krisch G. Monaco 《Journal of synchrotron radiation》2018,25(2):580-591
An end‐station for resonant inelastic X‐ray scattering and (resonant) X‐ray emission spectroscopy at beamline ID20 of ESRF – The European Synchrotron is presented. The spectrometer hosts five crystal analysers in Rowland geometry for large solid angle collection and is mounted on a rotatable arm for scattering in both the horizontal and vertical planes. The spectrometer is optimized for high‐energy‐resolution applications, including partial fluorescence yield or high‐energy‐resolution fluorescence detected X‐ray absorption spectroscopy and the study of elementary electronic excitations in solids. In addition, it can be used for non‐resonant inelastic X‐ray scattering measurements of valence electron excitations. 相似文献
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Due to high reflectivity and high resolution of X-ray pulses, diamond is one of the most popular Bragg crystals serving as the reflecting mirror and mono-chromator in the next generation of free electron lasers(FELs).The energy deposition of X-rays will result in thermal heating, and thus lattice expansion of the diamond crystal,which may degrade the performance of X-ray FELs. In this paper, the thermal loading effect of diamond crystal for X-ray FEL oscillators has been systematically studied by combined simulation with Geant4 and ANSYS, and its dependence on the environmental temperature, crystal size, X-ray pulse repetition rate and pulse energy are presented. Our results show that taking the thermal loading effects into account, X-ray FEL oscillators are still robust and promising with an optimized design. 相似文献