An investigation of matched cleavage faces of sodium chloride crystals

Abstract

An extension of the gold decoration technique has been devised whereby surface features on matching faces of vacuum cleaved rocksalt crystals can be studied at high resolution in the electron microscope. The system can be used in ultra high vacuum (10⁻⁸ torr) systems and both cleavage and decoration can be carried out at elevated temperatures if required. Some examples demonstrating the use of the method are discussed. Many of the surface structures can be explained on the basis of dislocation interactions with the cleavage crack. It is shown that the growth behaviour of the decorating islands at steps may be governed by the direction of impingement of gold atoms migrating across the surfaces.