Electron Paramagnetic Resonance Study of γ-Ray Irradiated Phosphate Glasses

The EPR spectrum, consisting of a two-line structure and two other distinct types of weak resonances, obtained from irradiated phosphate glasses suggests that these paramagnetic centers are connected with the peculiar structure of phosphate glasses. The two-line structure arises from an axiallysymmetric hyperfine interaction of a hole with a 31P nucleus. Two distinct types have been demonstrated: one is a trapped hole produced in the glass network, and the other is the trapped electron in the alkaline or alkaline earth ion. In phosphate glasses modified with such ions as calcium, barium or lithium that can coordinate with the tetrahedral oxygen atom in “End” groups (-PO3), the weak resonances seem to appear easily.