Ultraviolet, visible, ESR, and infrared spectroscopic studies of CeO2-doped lithium phosphate glasses and effect of gamma irradiation

UV-visible and FTIR spectroscopic properties of some prepared undoped lithium phosphate and CeO2-doped glasses of the same composition were measured before and after successive gamma ray irradiation. The undoped lithium phosphate glass exhibits strong ultraviolet absorption which is correlated with the presence of trace iron impurities within the raw materials used for the preparation of such glass. The undoped glass shows after gamma irradiation with 2 M rad, the broadness of the UV band with the resolution of two peaks at about 242 nm and 300 nm and the appearance of a small broad band centered at 514 nm. On further exposure to 5 M rad, the base glass exhibits a spectrum consisting of a broad UV absorption with two peaks at about 243 and 384 nm and three visible bands at about 404, 514 and 915 nm. CeO2-doped samples reveal the broadness of the UV absorption and the appearance of two bands at about 235 and 312 nm. Gamma irradiation on CeO2-doped glasses produces an extra induced visible band and show obvious shielding effect especially within the visible region but the UV absorption remains unaffected with two peaks at about 240 and 316 nm. Infrared absorption spectra of the prepared glasses reveal characteristic IR vibrations due to characteristic phosphate groups according to the glass composition and the effects of CeO2 or gamma irradiation are observed to be limited. ESR spectra of the unirradiated CeO2-doped glass show no specific signals while after gamma irradiation characteristic resonance is observed indicating the appearance of Ce3+ ions. (C) 2011 Elsevier B.V. All rights reserved.