Microdiffraction Calculations For Dislocations

Abstract

The new generation of STEM instruments offer the possibility of recording the diffuse elastic scattering from the core region of an isolated dislocation. In order to use this information for core-structure analysis it is important to be able to compute this scattering including all dynamical and instrumental effects. Preliminary results of such a calculation using the multi-slice method of periodic continuation (1) are shown in figures 1-4 for the case of an end-on [100] undissociated edge dislocation in iron. Theoretical core atom coordinates (2) have been used to form a periodic array of dislocations as shown in figures 1 and 2. These atomic coordinates are calculated for a single isolated dislocation, however the scattering from the periodic array of dislocations shown closely approximates that from an isolated dislocation if the illuminating spot is small compared to the superlattice unit cell. No relaxation has been allowed in the beam direction.