Radiation damage processes in insulating materials

Abstract

Transparent materials are especially useful in communication and electro-optics devices and laser and fiber optics systems. Radiation damage processes can be important in all of these uses. Therefore, it is necessary that an understanding of radiation damage processes be obtained through research. In this paper we will review the understanding of radiation damage processes in various types of materials. A brief review of the damage mechanisms in oxide materials will be given, but emphasis will be placed on radiation damage mechanisms in halide crystals. In particular, the production of vacancy-interstitial pairs in RbMgF 3 by high energy electron radiation will be discussed. Fortunately, the crystal structure of RbMgF 3 is such that vacancy motion does not occur until 400 K. This means that studies of F center formation without vacancy aggregation can be made even at room temperature. Subsequent annealing measurements can give insight into the formation of F aggregate centers. Moreover, some time ago it was discovered that the formation of F center-Mn 2+ impurity ion pairs gives rise to a distinctive set of absorption and emission spectra. It has also been found that in the radiation process, Mn 2+ ions can capture interstitials. The halide interstitial-Mn 2+ pairs also have characteristic spectra in absorption and emission. Through optical absorption and emission measurements, it is possible to investigate the formation and movement of interstitials at low temperature and to monitor the production of F center-Mn 2+ impurity ion pairs as they are formed. The information obtained from the production and dissolution of the various defect centers is used to evaluate the proposed models for radiation damage production in highly ionic materials.