Fringe Patterns at Anti‐Phase Boundaries with α = π Observed in the Electron Microscope

A study is made of the fringe patterns observed in transmission electron microscopy at anti‐phase boundaries or stacking faults with α = π. Use is made of the dynamic theory including anomalous absorption. The results are compared with observations of anti‐phase boundaries in titanium dioxide. The specific properties of the fringe patterns at π‐boundaries are discussed analytically and compared with those at 2 π/3‐boundaries. From these considerations, criteria can be established which distinguish π‐boundaries by their contrast features. Some computed profiles illustrate the agreement of this theory with observations on rutile. A discussion is included of the fringe characteristics at the intersection of bend faults. Finally, the contrast effects at parallel and intersecting overlapping faults are analysed.