UV–visible, Raman and E.S.R. studies of gamma-irradiated NiO-doped sodium metaphosphate glasses

UV–visible spectroscopic measurements of Ni-doped sodium phosphate glasses were carried out before and after successive gamma irradiation. The undoped glass reveals strong UV absorption originating from trace iron impurities. NiO-doped glasses show characteristic absorption bands due mainly to octahedral coordination of Ni2+ ions. Gamma irradiation produces induced bands generated from intrinsic defects and extrinsic defects.The changes in the spectroscopic data are discussed in relation to the structural evolution caused by the changes in composition and coordination state of nickel ions. The change in the growth behaviour of the induced bands is related to the annihilation or approach saturation of these characteristic induced bands.Raman and E.S.R. spectroscopic measurements confirm the presence of nickel as Ni2+ ions in octahedral state.