Optical absorption and photoluminescence properties of Er3+ doped mixed alkali borate glasses

An investigations of the optical absorption and fluorescence spectra of 0.2 mol% Er2O3 in mixed alkali borate glasses of the type 67.8B2O3·xLi2O(32 − x)Na2O, 67.8B2O3·xLi2O(32 − x)K2O and 67.8B2O3·xNa2O(32 − x)K2O (where x = 8, 12, 16, 20 and 24) are presented. The glasses were obtained by quenching melts consisting of H3BO3, Li2CO3, Na2CO3, K2CO3 and Er2O3 (950–1100 °C, 1.5–2 h) between two brass plates. Spectroscopic parameters like Racah (E1, E2 and E3), spin-orbit (ξ4f) and configuration interaction (α) parameters are deduced as function of x. Using Judd–Ofelt theory, Judd–Ofelt intensity parameters (Ω2, Ω4 and Ω6) are obtained. Radiative and non-radiative transition rates (AT and WMPR), radiative lifetimes (τR), branching ratios (β) and integrated absorption cross-sections (Σ) have been computed for certain excited states of Er3+ in these mixed alkali borate glasses. Emission spectra have been studied for all the three Er3+ doped mixed alkali borate glasses. The present paper throws light on the trends observed in the intensity parameters, radiative lifetimes, branching ratios and emission cross-sections as a function of x in these borate glasses, keeping in view the effect of mixed alkalies in borate glasses.