BERG-BARRETT X-RAY OBSERVATION OF DISLOCATIONS IN CHEMICALLY ATTACKED ZINC CRYSTALS

The Berg-Barrett X-ray diffraction contrast technique has been used to observe dislocation arrangements beneath the cleavage surfaces of pure zinc crystals after they had been subjected to either a particular chemical polishing treatment or a heavy etching. Three principal effects were noted: (a) the segmentation of existing dislocation lines by surface terracing, (b) the creation of hexagonal-shaped prismatic dislocation loops, and (c) the generation of shallow half-loops. The latter two observations seem important, for zinc, at least, because of the influence that chemical preparation techniques may have on the intrinsic" dislocation structure. © 1968."