On the kinematical theory of diffraction contrast of electron transmission microscope images of edge dislocations_

Hirach et al. (1960) have developed a kinematical theory for the diffraction contrast of the electron microscope image of a perfect screw dislocation parallel to the surface of the crystal foil. The present author (Gevers 1962 a, b) has extended their theory for a perfect dislocation of mixed type with slip plane parallel to the surface. In this paper the theory is applied to a partial screw dislocation parallel to the surface. Numerical calculations have been performed for n = ±1/3, ±2/3, ±4/3, ±5/3, ±7/3, ±8/3,where n = g . b (g: diffraction vector, b; Burgers vector). It is found that for |n| = 1/3 the line contrast is unimportant, probably negligible, that for |n| =2/3 an observable line image superposed on the stacking fault contrast should be present, and that for larger values of |n| the line contrast becomes much more important than the stacking-fault contrast.