The Fine Structure of Spots in Electron Diffraction Resulting from the Presence of Planar Interfaces and Dislocations. IV. Wedge Crystals

The fine structure of electron diffraction spots caused by the presence of wedge shaped crystal parts in a selected area, is derived theoretically and compared with observations. The same method has been applied in parts I and III i.e. a Fourier transformation of the transmitted and scattered intensities. Two general types of wedges are considered; wedges formed by grain‐boundary and twin boundary arrangements where only one crystal part is in a reflecting position and general wedges as e.g. the genuine wedges of geometrically shaped crystals. Normal and anomalous absorption are taken into account, as well as refraction effects in the case of a genuine wedge. MgO crystals and twin boundaries in stainless steel were used to compare the theoretical results with experiment. The observations are in very good agreement with the predicted fine structure.