A Dislocation Pinning in KCl Crystals Annealed in Chlorine Gas

Abstract

On KCl crystals annealed in chlorine gas, the internal friction was measured as a function of strain amplitude by the Marx’s method. The experimental results were analysed by the Granato-Lücke model of vibrating dislocations. It was found that the internal friction is remarkably decreased with X-irradiation. It was indicated that chlorine molecular ions introduced in crystals by the annealing were changed to pinning elements on the dislocations with the X-irradiation. With repeated measurements in the range exceeded the break points, the internal friction irreversibly increased. The fact was interpreted by vanishing of the pinning elements with breakaway of the dislocations from them. The pinning element was supposed to be chlorine molecule ion Cl₂⁻ captured on dislocation.