AN ELECTRON-SPIN-RESONANCE STUDY OF GAMMA-IRRADIATED BARIUM GALLIOSILICATE GLASSES

Electron-spin-resonance spectroscopy has been used to study the struct ure of radiation-induced defects in a barium galliosilicate glass comp ositional series of BaO/Ga2O3 = 1.0 and 20-80 mol % SiO2. Spin-Hamilto nian parameters derived from computer line-shape simulations have been used to identify three oxygen-associated hole centers: a gallium-oxyg en hole center and two variations of silicon-oxygen hole centers. Each of these defects contains an unpaired electron in a nonbonding oxygen p orbital. The compositional dependence of the ESR data is consistent with a gradual change from a Ga-based tetrahedral network to a Si-bas ed tetrahedral network as the silica content is increased.