The Transmission Electron Microscopy of Interfaces and Multilayers

The diversity of the types of structural boundary which have been studied by TEM is as wide ranging as are the methods available to the microscopist for their characterisation. The choice of the best technique to use, as well as an understanding of the limitations of each, can often thus be as important as the recognition of the specific characteristic of a given interface which is of most relevance in relation to the material properties investigated. Sometimes it is not even clear that the local heterogeneity of structure or chemistry of interest can actually properly be described as being delineated on the atomic scale by a discrete plane. Cases in point can be found in the study of amorphous structure, spinodal decomposition, short range order and the characterisation of icosahedral materials. We will examine in this area not only the relative usefulness of techniques such as high resolution microscopy and the weak beam method, but also come to realise that the method used can allow useful definitions for discreteness which parallel the modelling of the origins for the structural inhomogeneity.