Selective Etch for New Edge Dislocations in Sodium Fluoride

A simple etch consisting of a dilute aqueous solution containing manganous ions has been found to selectivity etch new edge dislocations in sodium fluoride. With this etch the new edge dislocations produced deep pits based on the icositetrahedral form, whereas all other dislocations yielded shallow cones. The selective etching action was decreased with increase of manganous ion concentration and with increase of the impurity content of the edge dislocation. The selective etching action is attributed to the combined effect of the elastic energy and the core energy of the new edge dislocation.