Effects of simultaneous displacive and ionizing radiations and of electric field on radiation damage in ionic crystals

We summarize our recent progress on the formation process of radiation-induced defects, their stability, and cation- and anion-disordering in ionic crystals, such as magnesium aluminate spinel and alpha alumina, under simultaneous displacive and ionizing radiations or under electric field. In those crystals, suppression of dislocation loop formation is observed under simultaneous ionizing and displacive radiations. Cation and anion disordering are also detected through newly developed analytica electron microscopy. Furthermore, the electric field suppresses the formation of dislocation loops and enhances their growth in thinner specimens of ionic crystals. Those results are discussed in terms of the instability of defect clusters under electronic excitation and displacements of structure vacancies and of the interaction between charged defects and electric fields.