0.25–30 kGy γ Irradiation-induced modifications on the density, optical absorption, thermo-, and photo-luminescence of the 10BaO–20ZnO–20LiF-49.3B₂O₃-0.7Er₂O₃ glass

The influence of 0.25–30 kGy γ doses on the 10BaO–20ZnO–20LiF-49.3B₂O₃-0.7Er₂O₃ glass was analyzed through the density, optical absorption, thermo-, and photo-luminescence. With a successive increase in the dose, the density of the glass increased, confirming radiation-induced compaction. The color of the glass deepened progressively with the increase in the γ dose, leading to the enhancement in the optical absorption. A continuous fall in the bandgap and an increase in the Urbach energy was also observed. The rise in the electron density with dose, caused a gradual upsurge in the covalency around the Er³⁺ ions, as inferred from the bonding parameter (δ), and the Judd-Ofelt parameters (Ω₂,Ω₄,Ω₆). The defects produced in the glass because of irradiation were evaluated using the trap parameters deduced from the Computerized Glow Curve Deconvolution and Chen's peak shape methods. The 30 kGy irradiated glass contained deeper traps when compared to the 0.25 kGy irradiated glass. The excitation spectrum recorded by monitoring the emission at 550 nm revealed the spectral transitions originating from the ground state ⁴I_15/2 of the Er³⁺ ion to ⁴G_9/2, ⁴G_11/2, (²G,⁴F)_9/2, ⁴F_5/2, and ⁴F_7/2 excited states, among which the ⁴I_15/2 → ⁴G_11/2 transition at 379 nm was very intense. In the emission spectra, one violet (²H_9/2→⁴I_15/2) and two green emissions (²H_11/2→⁴I_15/2 and ⁴S_3/2→⁴I_15/2) were detected out of which the ⁴S_3/2→⁴I_15/2 transition was the most prominent. The decrement in the intensity of this emission with dose was attributed to the radiation-induced quenching. The laser performance parameters computed by the Fuchtbauer-Ladenburg theory validated the emission quality of the irradiated glasses. The quantum efficiency did not fall below 60% for all the doses. The color coordinates were clustered in the green region and showed not much variation with dose. The present study manifests the remarkable radiation hardness of the titled glass as a green emission device and laser.