Effect of dose rate, temperature and impurity content on the radiation damage in the electron irradiated NaCl crystals

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 2000-05, Vol.166-167, p.561-567
• Main Authors: Dubinko, V.I., Turkin, A.A., Vainshtein, D.I., den Hartog, H.W.
• Format: Article
• Language: English
• Subjects: Alkali halides; Bubbles; Colloids; Radiation damage; Voids
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/S0168-583X(99)00722-3

The dependencies of void formation and radiolytic sodium accumulation on the irradiation dose, dose rate, temperature and impurity content are analyzed within a framework of a theoretical model, which is based on a new mechanism of dislocation climb. The mechanism involves the production of VF centers (self-trapped hole neighboring a cation vacancy) as a result of the absorption of excess H centers at dislocation lines. Voids are shown to arise due to the reaction between F and VF centers at the surface of halogen bubbles. All reactions involved in the evolution of extended defects are controlled by the difference between the absorption of H centers and F centers. This difference is determined by the material specific parameters responsible for the bias factors of extended defects and by the mean concentration of point defects. The latter depends on the temperature and dose rate as described in the present paper. Impurities can facilitate or suppress radiation damage formation depending on their effect on the nucleation of extended defects under irradiation. This is demonstrated by comparing theoretical results obtained for dose dependence of colloid volume fraction at different dislocation densities with experimental data obtained in crystals doped with different impurities.