Influence of ZnF2 and ZnCl2 on luminescence investigations and crystal field calculation of Eu3+ doped zinc oxide-phosphate glasses

Abstract

A series of Eu3+-doped 70NaPO3–20ZnO-10(ZnF2/ZnCl2) glasses were prepared by conventional melting quenching method. The samples were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), electron probe microanalysis (EDS/WDS) and optical spectroscopy. Using the emission spectra a set of Judd-Ofelt (JO) intensity parameters (Ω2, Ω4, Ω6) was refined, which in turn permitted to calculate transition probabilities (AED, AMD), branching ratios (β), radiative lifetimes (τrad) and stimulated emission cross-sections for the 5D0-7FJ transitions. The relative luminescence intensity ratio of 5D0-7F2-5D0-7F1 transitions has been evaluated to estimate the local site symmetry around the Eu3+ ions. Second and fourth rank crystal-field (CF) parameters together with the CF strength parameter have been reported for the first time for such study by assuming the C2v symmetry for the Eu3+ ions in both the phosphate glasses. Large stimulated emission cross-section, high branching ratios and quantum efficiencies (∼80%), also, intense red luminescence at 616 nm confirm that these present glasses suggesting for visible red lasers materials and optical devices.