ISSN:0741-0581    

DOI:10.1002/jemt.1060130103

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe purpose of this article is to present a practical guide to the identification of phases in the analytical electron microscope with the aid of convergent beam electron diffraction. There is included a step‐by‐step approach to phase analysis, from the possible choices of the form of the specimen through how to explore reciprocal space in order to perform a full phase identification, either by symmetry analysis or by simple comparison of a pattern observed in the microscope with a previously recorded pattern (fingerprinting). There is a strong emphasis on practical hints and useful shortc

ISSN:0741-0581    

DOI:10.1002/jemt.1060130104

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe ability to obtain diffraction patterns with a large angular view has significantly enhanced the ease and potential of electron diffraction studies in the determination of unit cells and identification of submicron phases. Convergent beam electron diffraction (CBED) provides a two‐dimensional projection of the three‐dimensional reciprocal lattice and can be utilized to reconstruct the unit cell dimensions. In particular, the spacing of the reciprocal lattice layers parallel to the electron beam and the location and distribution of the reflections in the first and higher order Laue zones with respect to the zero layer provide information which cannot be obtained from the zero layer pattern alone. This additional information permits the identification of crystal structures of phases under investigation with previously established ones or the determination of new structure, if previously unknown. The article describes the principles of the analysis and illustrates the application of the methods with examples from commercial material syst

ISSN:0741-0581    

DOI:10.1002/jemt.1060130105

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe crystal point‐ and space‐group determination method using convergent‐beam electron diffraction (CBED) is reviewed. Crystal symmetry elements that can be observed by CBED are disc

ISSN:0741-0581    

DOI:10.1002/jemt.1060130106

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe techniques required to record standard convergent beam electron diffraction patterns in an analytical electron microscope are discussed in detail, with emphasis on the design of electron optics in commercial instruments. Practical comments are included on specimen preparation, the influence of crystal defects, tilting to major zone axes, and alignment of the instrument. The influence of parameters under experimental control such as probe size, accelerating voltage, temperature, specimen tickness, and convergence angle is discussed in detail. Some comments are included on the alignment and limitations of large angle patterns formed by a defocused probe.

ISSN:0741-0581    

DOI:10.1002/jemt.1060130107

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

年代:1989

数据来源: WILEY

摘要:

AbstractA brief review is presented of the methods of measuring lattice parameters and strain using diffraction techniques. The presence of strain leads to broadening of diffraction maxima, which is normally separable from any broadening caused by size. The special advantages of the convergent beam electron diffraction (CBED) techniques in measuring lattice parameters and strain are given from studies of precipitation (including misfit measurements) and from investigations of partially recrystallised microstructures. These examples are used to illustrate the advantages and limitations of the CBED technique.

ISSN:0741-0581    

DOI:10.1002/jemt.1060130108

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe methods by which Convergent Beam Electron Diffraction (CBED) is used to solve practical problems in materials science are reviewed. Particular emphasis is placed on those applications where a consensus has developed on the potential difficulties, but these problems have never been explicitly treated in the literature. Point‐group determination using CBED is a standard technique, but there are several different experimental methods which are outlined here; the different approaches and the information obtained are compared. These point‐symmetry determinations are shown to rely heavily on elimating the large number of potential artefacts: the possible sources of symmetry‐breaking are summarised, and their salient features are identified. This should give a prescription for demonstrating whether symmetry‐breaking arises through crystal structure, defects, strain, or specimen morphology. In space‐group determinations the practical approach is now fairly standard, but the article draws attention to some anomalies. Strain and lattice parameter determinations are also standard, but a consensus is beginnning to emerge that the interpretive difficulties involved in allowing for thin film relaxation are extremely severe: a few of these difficulties are outlined. Finally, the article also addresses some of the techniques which have been used to extract structural or compositional information from CBED: the experimental approach depends on the specific problem, and the article aims to provide some examples to illustrate what is

ISSN:0741-0581    

DOI:10.1002/jemt.1060130109

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

年代:1989

数据来源: WILEY

ISSN:0741-0581    

DOI:10.1002/jemt.1060130102

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

年代:1989

数据来源: WILEY