Direct observation of defects in evaporated silver

Abstract

Single-crystal films of silver were made by evaporation of silver onto the cleavage surface of a heated rock-salt crystal. The crystalline defects present in the detached films were studied by transmission electron microscopy. In fresh areas of the foil, numerous simple stacking faults confined to a single plane were observed. The number varied between 5 × 10⁹ and 1 × 10¹⁰ cm⁻². There was a strong tendency for the partial dislocations to lie in 〈110〉 directions. The morphology of the simple fault shapes resulting is considered in detail. Electron beam stressing resulted in the dissociation of whole dislocations and in the widening of faults already present. The interaction of the faults to form complex faults on several planes, and the effects of holes and dislocations were studied. Some areas showed minor defects consisting of dislocation loops and tetrahedral stacking faults. Preliminary annealing experiments indicate that the simple faults are remarkably stable at 300°c. The origin of the various defects is discussed. It is concluded that most simple faults probably form by dissociation of dislocations which may (1) grow in from the substrate, (2) nucleate at silver patch edges during growth, (3) form by impingement of patches on a {110} plane during growth.