Abstract
The 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 beginning 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 possible.
Published Version
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