8 - Mineralogical applications of TEM – I. Defects and microstructures in undeformed specimens

Summary

Introduction

The previous chapters have given an account of the essential physics of the transmission electron microscope and of the basic concepts and theories of electron diffraction that are required for interpretation of the images of crystalline materials, especially when these materials are structurally imperfect due to the presence of various types of point, line, and planar defects. The specific aim of this chapter and the next is to discuss some characteristic examples of the images of the various types of defect and defect microstructures that have been observed in a range of important rock-forming minerals. Although emphasis is placed on the nature of the images and their interpretation, rather than on the relevance of the various types of defects and microstructures to mineralogical properties and processes, these latter aspects are not entirely neglected.

The examples in this chapter cover a wide range of defects and microstructures, from the simpler type of planar defect (such as the stacking fault) to the defects associated with radiation damage. The following chapter deals with dislocations and the complex microstructures associated with plastic deformation. In both chapters, the examples are presented in a sequence that attempts to link them as much as possible in order to bring out the relationships, similarities, and differences among the various types of crystal defects from the points of view of their image contrast, structure, and origin.