Centers and mechanisms in ionic materials

Point defects in ionic materials have been briefly reviewed. The main types of intrinsic defects, together with some representative examples of impurity related defects are described. Several mechanisms of center production, destruction and transformation are discussed. The main spectroscopic techniques, such as optical absorption, photo-and thermo-luminescence and magnetic resonances, used in the study of these defects and the results obtained with these techniques in some simple cases are also presented. (author)