Preparation and characterization of invert ZnO–B2O3 glasses and its shielding behavior towards gamma irradiation

Abstract

Binary zinc borate glasses with invert compositions (50–75 mol % ZnO) were prepared by melting and annealing technique. The glasses were collectively characterized by measuring and identifying their structural building groups through FTIR spectroscopy and their optical transparency beside also their thermal expansion parameters. FTIR spectra reveal compact vibrational bands within the mid region 400-1700 cm−1 reflecting both triangular and tetrahedral borate groups beside the sharing of ZnO as either modifier oxide or as B–O–Zn linkages and possibly ZnO4 groups. The optical absorption measurements reveal that the studied undoped ZnO–B2O3 glasses show distinct UV absorption extending from 200 to 370 nm with three peaks and these UV absorption peaks are related to unavoidable trace iron (Fe3+) impurities contaminated within the chemicals used for the preparation of the zinc borate glasses. The optical absorption spectra after gamma irradiation with a dose of 5 Mrad reveal the maintenance of the UV spectra identified before irradiation with the appearance of a minor curvature at 510 nm in the spectra of two samples and disappeared at high ZnO contents. Such optical spectral result after irradiated refers to suggested shielding effect towards gamma irradiation with high ZnO content in the studied invert compositions. Both the dilatometric softening temperatures and density data show obvious increase with the first increase of ZnO content up to 70% and then reveal constancy. This behavior is correlated with the mode of housing Zn2+ ions in the network structure which is assumed to form some ZnO4 groups at high percent of ZnO giving compactness to the network of such glasses.