Dislocations Observed in NaF Crystals. I. Rosette Structure and Its Changes under External Stress

Abstract

Three dimensional observation of individual dislocation lines constituting indentation rosette was made by electrolytic decoration. The majority of lines belonged to systems of loop families of {110} and {112}. From the structure, the formation of rosette was inferred to consist of the initial stage where the elemental glides operate, and the rearrangement stage where cross glide, climb, multiplication and network formation also operate. Upon applying external stress by bending and compression the rosette structure transformed to an arrangement more complicated than that expected. Causes of the complication are the plastic deformation and residual strains around indent. Mechanical and electrostatic motives may explain the characteristic transformation.