Optical and luminescence properties of Dy3+ ions in phosphate based glasses

Phosphate glasses with compositions of 44P(2)O(5) + 17K(2)O + 9Al(2)O(3) (30 - x)CaF2 + xDy(2)O(3) (x = 0.05, 0.1, 0.5, 1.0, 2.0, 3.0 and 4.0 mol %) were prepared and characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), Fourier transform infrared (FTIR), optical absorption, emission and decay measurements. The observed absorption bands were analyzed by using the free-ion Hamiltonian (H-FI) model. The Judd-Ofelt (JO) analysis has been performed and the intensity parameters (Omega(lambda), lambda = 2, 4, 6) were evaluated in order to predict the radiative properties of the excited states. From the emission spectra, the effective band widths (Delta lambda(eff)), stimulated emission cross-sections (sigma(lambda(p))), yellow to blue (Y/B) intensity ratios and chromaticity color coordinates (x, y) have been determined. The fluorescence decays from the F-4(9/2) level of Dy3+ ions were measured by monitoring the intense F-4(9/2) -> H-6(15/2) transition (486 nm). The experimental lifetimes (tau(exp)) are found to decrease with the increase of Dy3+ ions concentration due to the quenching process. The decay curves are perfectly single exponential at lower concentrations and gradually changes to non-exponential for higher concentrations. The non-exponential decay curves are well fitted to the Inokuti-Hirayama (IH) model for S = 6, which indicates that the energy transfer between the donor and acceptor is of dipole-dipole type. The systematic analysis of revealed that the energy transfer mechanism strongly depends on Dy3+ ions concentration and the host glass composition. (C) 2013 Elsevier Masson SAS. All rights reserved.