RADIATION-INDUCED PARAMAGNETIC CENTERS IN NUCLEAR GLASSES BY EPR SPECTROSCOPY

An electron paramagenetic resonance (EPR) investigation of a series of glasses irradiated at room temperature with beta or X radiation sourc es has been made in order to predict the long term behavior of glasses used in the nuclear waste disposal. EPR spectra of the irradiated gla sses have been measured and treated using computer simulations. Simula tion of the g factor and hyperfine interaction distributions have led to the identification of different paramagnetic centers in these irrad iated glasses. The following paramagnetic defects were identified: bor on oxygen hole center (BOHC), HC1 center, two different hole centers, peroxy radical (Oxy defect), E' centers, and electron trapping process es for iron and zirconium ions: Zr4+ + e(-) --> Zr3+ and Fe3+ + e(-) - -> Fe2+. In particular, no paramagnetic defects associated with alumin um ions are detected in these irradiated glasses. (C) 1998 Elsevier Sc ience B.V. All rights reserved.