Effect of Cleavage on the Dislocation Content of Sodium Chloride

Cleavage of sodium chloride crystals is found to increase the dislocation content of the crystals in the region of the cleavage. Evidence is shown of bands of high dislocation content in large crystals, and for over‐all increase in dislocation content for thin crystals. It is proposed that the dislocations produced are perpendicular to the cleavage plane and require that strains produced by cleavage are sufficient for the production of new dislocations and for the movement of inherent dislocations.