The dependence of void formation upon the irradiation dose, dose rate, temperature and impurity content was analyzed by using a theoretical model which was based upon a new mechanism for dislocation climb. This mechanism involved the production of VF centers (self-trapped hole neighboring a cation vacancy) resulting from the absorption of excess H centers at dislocation lines. The voids were shown to arise due to reactions between F and VF centers at the surfaces of halogen bubbles. The reactions which were involved in the evolution of extended defects were controlled by the difference between the absorptions of H centers and F centers. This difference was governed by the material parameters which were responsible for the bias factors of extended defects, and by the mean point-defect concentration. The latter depended upon the temperature and dose rate. The presence of impurities could aid or suppress radiation damage; depending upon their effect upon the nucleation of extended defects during irradiation. This was shown by comparing theoretical predictions, for the dose-dependence of colloids at various dislocation densities, with experimental data.

Effect of Dose Rate, Temperature and Impurity Content on the Radiation Damage in Electron Irradiated NaCl Crystals. V.I.Dubinko, A.A.Turkin, D.I.Vainshtein, H.W.den Hartog: Nuclear Instruments and Methods in Physics Research B, 2000, 166-167, 561-7