The twist and distortion, caused by dislocations, of diffraction fringes in convergent-beam electron diffraction patterns were studied. It was found that the sense of the twist reversed when the beam cross-over changed from one side of the specimen to the other. On the basis of qualitative considerations, it was concluded that the diffraction fringes on the side towards which the vector, u x c, pointed were shifted along b. This phenomenon could be used to determine the sign of the Burgers vector of a dislocation.

F.Niu, R.Wang, G.Lu: Acta Crystallographica A, 1991, 47[1], 36-9