Shielding behavior of MoO3-doped lead borate glasses towards gamma irradiation assessed through collective optical, FTIR, and ESR spectral analysis

Abstract

Glasses from the base binary lead borate (70PbO–30B2O3 wt%) and samples containing additional (0.2, 0.5, 0.75 wt% MoO3) were prepared by normal melting-annealing technique. Characterization of the optical, FTIR, ESR spectral properties of the prepared glasses were measured before and after been subjected to gamma irradiation (6 Mrad). Optical spectra of the glasses revealed pronounced UV absorption bands extending from 200 to 330 nm for the base undoped glass and extended within the UV to additional bands at 360 and 390 nm in the MoO3-doped glasses. The collective UV absorption bands were related to both unavoidable contaminated trace iron impurities (Fe3+) together with absorption due to divalent lead ions (Pb2+). With MoO3- doped glasses, the hexavalent state was assumed to be dominant due to the absence of any visible bands and only two extra UV bands are identified. FTIR spectra showed distinct vibrational bands due to triangular and tetrahedral borate groups in their different characteristic wavenumbers. Beside the sharing of some PbO4 but the two borate groups are highly identified due to the ease of mobility and vibrations of the borate groups containing the lightest weight boron element in glass forming oxides. The addition of MoO3 caused minor effect on the FTIR spectra, because of their low doping percent. Gamma irradiation caused the disappearance of some UV peaks and this was correlated with suggested photochemical reactions and similar behaviour was correlated with the ESR measurements after irradiation. Both spectral data indicated the presence of molybdenum mainly in the hexavalent state. FTIR spectra after irradiation confirmed the stability of the studied high metal oxide lead borate glasses, i.e. their shielding behaviour towards gamma irradiation.