Structural and spectroscopic properties of γ-ray irradiated Er3+-doped lead phosphate glasses

Abstract

Structural and spectroscopic properties of varying concentrations of Er3+ ion in P2O5- PbO-K2O-Al2O3-Na2O (PPbKANEr) glasses were studied before and after consecutive γ-ray irradiation. FTIR spectra of all the contemplated glasses confirm the presence of characteristic vibrational bands mainly because of phosphate groups. The optical absorption spectra of Er2O3-doped glasses are more stable and do not exhibit any variations after γ-ray irradiation particularly when Er3+ ions are present in higher concentrations. Judd-Ofelt (JO) analysis was carried out for γ-ray irradiated glasses and the resultant three phenomenological intensity parameters were found to be Ω2 = 1.98, Ω4 = 0.78 and Ω6 = 1.24 (×10–20 cm2). A bright emission corresponding to 4S3/2 → 4I15/2 transition in the green region was observed with the excitation of 379 nm. Broad luminescence peak at 1535 nm (4I13/2 → 4I15/2) are observed in the region of 1400–1700 nm with the excitation of 980 nm. The important spectroscopic properties such as absorption (σabs(λ)) and emission cross-sections (σemi(λ)), gain band width (FWHM × σemi(λ)) for 4I13/2 → 4I15/2 transition at 1.53 µm were assessed for γ-ray irradiated PPbKANEr1.0 glass and the values found to be 6.73 × 10–21 cm2, 7.33 × 10–21 cm2 and 264 × 10–28 (cm3), respectively. The decay curves for the 4I13/2 → 4I15/2 transition of the γ-ray irradiated PPbKANEr glasses exhibit exponential nature and the lifetimes found to be decreased (3.72–0.62 ms) with the increasing Er2O3 concentration (0.05–4.0 mol%). The upconversion luminescence spectra exhibit two emissions at 525 nm (2H11/2 → 4I15/2) and 543 nm (4S3/2 → 4I15/2) in the green region along with a fairly feeble red emission at around 650 nm (4F9/2 → 4I15/2).