Influence of ZnF 2 and ZnCl 2 on luminescence investigations and crystal field calculation of Eu 3+ doped zinc oxide-phosphate glasses

A series of Eu 3+ -doped 70NaPO 3 –20ZnO-10(ZnF 2 /ZnCl 2 ) 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 (Ω 2, Ω 4, Ω 6 ) was refined, which in turn permitted to calculate transition probabilities (A ED, A MD ), branching ratios (β), radiative lifetimes (τ rad ) and stimulated emission cross-sections for the 5 D 0 - 7 F J transitions. The relative luminescence intensity ratio of 5 D 0 - 7 F 2 - 5 D 0 - 7 F 1 transitions has been evaluated to estimate the local site symmetry around the Eu 3+ 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 C 2v symmetry for the Eu 3+ 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.