Formation and Decay of Colour Centres in a Silicate Glasses Exposed to Gamma Radiation: Application to High-Dose Dosimetry

Abstract

The interactions of ionizing radiation with glass matrix produce ionization, excitation, and atomic displacement. The main modification induced during ┛, X rays, or electron irradiation on the glass structure is the creation of stable defects and the changes of the valence state of lattice atoms or of the incorporated impurities in glass. Some of the modified electronic configurations or defects cause preferential light absorption. Thus, glass becomes coloured and consequently these defects are called centres. These centres are of many types and depending on the glass composition (Yokota, 1954, 1956) and are associated with optical absorption bands and EPR signals. The change of optical properties of glasses when subjected to ionizing radiation has been investigated by many authors due to wide applications of this kind of material. The earlier studies were focused on ways to prevent the darkening in glasses used in reactor or hot-cell windows and optical devices (Friebele, 1991). Recently, many studies have been concentrated on the application of the irradiation induced colour to develop recyclable colour glasses which is of great interest in the glass industry from the economical and environmental point of view (Sheng et al., 2002a). In addition to the applications mentioned above, the ionizing radiation induced colour centres in some glasses have been found wide application in radiation dosimetry (Farah et al., 2010; Fuochi et al., 2008, 2009; Mejri et al., 2008). This material is very interesting for dosimetry and very useful for many applications such as food irradiation, sterilization of medical devices, radiation treatment of industrial and municipal waste-water and radiation processing of materials. In the present work, we investigated the effect of the irradiation dose and thermal annealing on the formation and the decay of the induced colour centres in gamma irradiated silicate