Diffraction from periodic arrays of dislocations

Abstract

The possibility of determining the core structure of a screw dislocation using crystal structure analysis techniques is considered. It is demonstrated that the structure factor of a square grid of screw dislocations is quite sensitive to the atomic configuration in the core. In principle, if the intensities of a sufficient number of dislocation reflections can be measured, it should be possible to determine the core structure of a screw dislocation. The existence of diffuse streaks normal to the plane containing the dislocation network is predicted. By comparison of the measured and computed diffuse streak profiles it should be possible to determine whether a variation in plane spacing along the direction normal to the boundary is present, and its magnitude. Because multiple diffraction has such a strong effect on electron diffraction intensities, it appears that X-ray diffraction is the best technique for measuring the dislocation reflection intensities.