Characterization of WO3-doped borophosphate glasses by optical, IR and ESR spectroscopic techniques before and after subjecting to gamma irradiation

Borophosphate glasses containing increasing WO3 within the doping level (0.16-1.33%) have been prepared and investigated by UV-visible, infrared spectral measurements. These glasses have been exposed to gamma rays with a dose of 8 Mrad for studying the effect of gamma radiation on the combined studied spectra of such glasses. The optical spectrum of undoped borophosphate glass reveals strong UV absorption but with no visible bands. This strong UV absorption is related to the presence of unavoidable trace iron impurities within the chemicals used for the preparation of this borophosphate glass. The WO3-doped samples show two additional UV and visible bands at about 380 and 740 nm due to the presence of both W6+ and W5+ ions in noticeable content. The calculated induced spectra reveal the appearance of an ultraviolet band at 320 nm and two visible bands centered at 390 and 540 nm which are related to the combined presence of W6+ and W5+ ions. The FTIR spectra show vibrational bands due to characteristic constitutional phosphate and borate groups but the phosphate groups are predominant due to the high P2O5 content (50%). The effect of the addition of WO3 with the dopant level reveals limited changes in the IR spectra. Electron spin resonance (ESR) spectra show specified signals in the high WO3 content glass but on gamma irradiation the signals are disappeared. This result confirms the decrease of the W5+ ions by photochemical oxidation to paired W6+ ions. This result is also observed in optical absorption of WO3 doped glasses after gamma irradiation through the disappearance of the visible band at 740 nm. (author)