Mechanism of void growth in irradiated NaCl based on exiton-induced formation of divacancies at dislocations

We propose a mechanism of void growth in di-atomic ionic crystals due to agglomeration of divacancies produced by interactions between dislocations and excitons. An exciton can cause movement of nearby dislocation jogs, resulting in the creation of equal numbers of anion and cation vacancies (Schottky defects). Owing to the heat generated locally during the exciton annihilation, the jog can be displaced while a divacancy arises in the lattice. Subsequent diffusion and agglomeration of divacancies can result in void formation and growth. We evaluate the void nucleation and growth rates in electron irradiated NaCl. (C) 2004 Elsevier B.V. All rights reserved

New mechanism for radiation defect production and aggregation in crystalline ceramics

In many ceramic solids, the number of primary displaced ions is different for different sublattice components, either because the ion masses and displacement energies differ in simple binary collisions (like in alumina) or because radiolytic displacements occur on a single sublattice (like in halides). However, irradiation produces not only metal colloids or gas precipitates, but stoichiometric dislocation loops, and voids as well. We propose a secondary displacement mechanism of vacancy production at a dislocation as a result of its interaction with a primary interstitial ion in another sublattice which explains the observed phenomena. (C) 2001 Elsevier Science B.V. All rights reserved

Kinetics of back reaction between radiolytic products initiated by radiation-induced voids in NaC1

A time-dependent model is formulated for the chemical reaction between sodium colloids and gas bubbles, which are brought into contact with each other by the growing voids. It is shown that in this exothermic reaction, heat is released much faster than it is dissipated by conduction to the surrounding salt. This results in a large and sudden temperature and pressure increase in the void, which is analysed in detail. The effect on the mechanical stability of NaCl under irradiation is discussed