Preparation of low dislocation density and dislocation-free zinc and copper single crystals

Abstract

We discuss the effect of growth conditions of Zn and Cu single crystals on their dislocation structure. The perfection of single crystals of pure metals grown from the melt is greatly determined by thermal stresses. A reduction of thermal stresses below a certain critical level produces dislocation-free crystals of copper. In addition, the nonequilibrium vacancy concentration is shown to influence the development of dislocation structures in Zn single crystals. A lower perfection of Zn single crystals than that of Cu crystals grown under similar conditions can be attributed to higher thermal stresses caused by the lattice anisotropy and to a higher efficiency of vacancies for the development of the dislocation structure.