ISSN:0741-0581    

DOI:10.1002/jemt.1060030102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0741-0581    

DOI:10.1002/jemt.1060030103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe factors defining the resolution limit and the conditions for obtaining images at atomic resolutions are briefly discussed. The construction and performance of a 400 kV analytical atom resolution electron microscope (AARM), and the functions of an energy selecting microscope, X‐ray micro‐analysis, and on‐line image processing systems are described. Some examples of applications of the AARM are

ISSN:0741-0581    

DOI:10.1002/jemt.1060030104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractBecause of the high brightness of the cold field emission source used in a dedicated scanning transmission electron microscopy (STEM) instrument, it is possible to focus electrons to a cross‐over of width 3Å or less and, with a suitable detection system, to obtain diffraction patterns from specimen regions of this size or greater. Coherent interference effects are visible in shadow images (in‐line holograms) and in convergent beam diffraction patterns. Special techniques have been developed for gathering information from the diffraction patterns for application to the study of the structures of crystal defects, crystal surfaces and small particles. Possibilities have been explored for holographic reconstruction from shadow im

ISSN:0741-0581    

DOI:10.1002/jemt.1060030105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractAmorphization induced by electron irradiation in Ni–50 at% Ti crystals has been investigated by electron microscopy. In order to clarify successive stages of amorphization, micrographs were taken in vairous regions where the total dose of electrons was continuously changed. Contrast was manipulated by changing the reflecting condition. Results obtained are summarized as follows: (a) Amorphization occurs inhomogenously; (b) there is a critical size, i.e., about 5 nmø in the crystals, for observing sharp lattice images in small blocks; (c) lattice images change to short and wavy fringe contrasts when the block size becomes smaller than the critical one, and finally they disappear; and (d) boundary contrast of the blocks rapidly decreases with decreasing size, and is hardly observed when the size becomes smaller than the critical one. Based on the results, the cause of abnormal fringe contrasts in fine blocks, the amorphization process, and atomic structures of amorphous materials are discuss

ISSN:0741-0581    

DOI:10.1002/jemt.1060030106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractWe found that high resolution electron microscopy has the following merits in the study of alloy structures: (1) New phases too small to be studied by x‐rays, such as σ‐related phases, may be studied; (2) local and highly disordered structures, such as domain boundaries and domains of only a few unit cells, are more easily studied; and (3) it is easier to order solute atoms, such as Ti atoms columns in C

ISSN:0741-0581    

DOI:10.1002/jemt.1060030107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe determination of the structures of catalysts is an important step in understanding their behaviour and in developing new or improved catalysts. By their nature, catalysts mostly have a structure which can be resolved only by transmission electron microscopy (TEM) used near its limit of applicability. This article discusses recent selected examples of the use of TEM to examine materials used as catalysts, such as clusters of atoms, small crystalline particles, the materials (oxides) on which these are supported, zeolites, and deposits of carbon which often form on catalysts during catalytic reactions. Interpretation of the images is often aided by the techniques of image processing.

ISSN:0741-0581    

DOI:10.1002/jemt.1060030108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractTo be successful, today's electron microscopist must have modern, well‐maintained facilities and be part of a team of experts with specific skills for research. Furthermore, in an ideal situation specific instruments should be dedicated to specific applications (high resolution, analytical, conventional, etc.), since in general the efficiency of a microscope varies inversely as its operations (and operators?). This is partly a reason for establishing national or regional electron microscopy centers, so that expertise and expensive equipment may be made available in central facilities.In this brief summary an attempt is made to illustrate how sophisticated methods of electron microscopy can be applied to practical problems by choosing representative examples from research at Berkeley using high resolution, high voltage, diffraction, and analytical techniques. More detailed examples have been given in some recent reviews (Thomas, 1984a, and Gronsky et al., 1985

ISSN:0741-0581    

DOI:10.1002/jemt.1060030109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA personal account is given of the development which led to the observation of dislocations in thin crystals by transmission electron microscopy in the mid‐1950

ISSN:0741-0581    

DOI:10.1002/jemt.1060030110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA simple theory is presented to explain the origin of two‐beam lattice fringes and to show how they can be used to derive the displacement vector of planar interfaces. The theory may have some value for pedagogical purposes since it provides some insight and emphasizes the similarity with optical interference experiment

ISSN:0741-0581    

DOI:10.1002/jemt.1060030111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY