Optical study of Ce3+ ion in gamma-irradiated binary barium-borate glasses

Absorption spectra measurements of cerium-doped binary system from barium-borate glasses have been measured. The effects of dopant concentration of CeO2 and Al2O3 in the concentration range 0.54–2.9 and 4.8–9.2 mol%, respectively, and exposed to different irradiation doses have been measured in the range 1–7 eV and the result have been interpreted in terms of structural concepts. The radiation-induced broad band at 2.25–1.88 eV in the base glass is observed to be suppressed by the presence of cerium due to the transformation of Ce4+ to Ce3+. The released electrons are then used to annihilate positive holes responsible for this band. The resolution of the observed absorption spectra show two to seven induced bands depending on the glass composition. Absorption spectra of the irradiated binary glass system are found to be controlled by the cerium concentration. From the absorption edge studies, the values of optical band gap Eopt and Urbach energy ΔE have been evaluated. The oxidoreduction (redox) reaction Ce3+/Ce4+ is assumed to be related to the glass basicity and the possible complex-ion formation. The oxygen ion activity (O2−) is believed to be related to the basicity and to the possible oxygen ion formation in the glass melt, and the redox equilibrium is shifted toward the reduced state.