Optical spectroscopy of Dy3+ doped borate glasses for luminescence applications

Dy3+ ion embedded in (50-x)B2O3-20PbO-15MgF(2)-15NaCl-xDy(2)O(3)(x = 0.2, 0.4, 0.6, 0.8, 1.0 and 2.0 mol%) borate glasses are prepared and investigated using Differential Thermal Analysis (DTA), X-ray Diffractometer (XRD), Raman spectra, optical absorption and photoluminescence (PL) as function of different concentrations. Thermal stability of borate glass has been calculated from DTA profiles. The amorphous nature of glass matrix is confirmed by XRD. Based on Raman spectra, the functional groups that are present in the glass matrices have been analyzed. Based on the Judd-Ofelt theory, three spectral intensity parameters Omega(lambda) (lambda = 2, 4, 6) are calculated from absorption spectra. These parameters are used to determine radiative transition probabilities (A(R)), radiative lifetimes (tau(R)) and branching ratios (beta(R)) of Dy3+ transitions from the excited state manifolds to corresponding lower laying multiplet manifolds. PL spectra show two intense and one weak band due to F-4(9/2) -> H-6(15/2) (blue), H-6(13/2) (yellow) and H-6(11/2) (red) transitions respectively. For these transitions luminescence properties are studied. With the increase in the concentration of Dy3+ ions, intensity increases up to 0.8 mol% and then concentration quenching is observed. This is (0.8 mol%) the optimized concentration for the present prepared glasses. Lifetimes (tau(exp)) are calculated for all the glass matrices from decay curve analysis. Spectroscopic and luminescence properties at 0.8 mol% doped dysprosium ion are compared with other reported glass matrices. From the above analysis suggest that 0.8 mol% of Dy3+ doped borate glasses can be useful for yellow lighting applications in the visible spectral region. (C) 2015 Elsevier B.V. All rights reserved.