Activation energy of dissolution at emergent dislocations

Abstract

Rates of deepening of dislocation-etch-pits at the (001) cleavage faces of single crystals of NiSO₄,6H₂O were measured by two-beam interferometry. By comparison with the rate of general dissolution of the surface in ethanol, it is shown that a significant decrease in activation energy (95 in 211 kJ mol^–1) is associated with preferential dissolution at an emergent dislocation. It is probable that the core energy, rather than the elastic strain energy of the dislocation, is the principal cause of the decrease.