Emission spectra and energy transfer studies in Dy3+ and Dy3+/Eu3+ co-doped potassium fluorophosphate glasses for white light applications

Potassium fluorophosphate (KFP) glasses doped with different concentrations of Dy3+ ions and co-doped with Eu3+ ions were prepared to study the luminescence spectra. Optical transition properties of Dy3+ doped KFP glasses were assessed with the aid of Judd-Ofelt (J-O) theory. Visible luminescence spectra have been obtained for Dy3+ ions and Eu3+ ions under 350 nm excitation. Yellow emission of Dy3+ was exhibited mainly due to the transition F-4(9/2)-> H-6(13/2) centered at 573 nm. Energy transfer between Dy3+ and Eu3+ ions and decay curves of Dy3+ and Dy3+/Eu3+ co-doped KFP glasses have been studied using fluorescence spectra. The decay of F-4(9/2) excited level is found to be single exponential for lower concentrations up to 0.3 mol% and becomes non-exponential for (greater than 0.3 mol%) higher concentrations. It is noticed that with the increase of Dy3+ concentration, the lifetime values of (4)F(9/2)( )level was decreased. Intense Reddish orange light was observed in addition to blue and yellow luminescence in these glasses. CIE chromaticity coordinates were calculated to study the generation of white light from the luminescent transitions. The results of this experiment show significant promise for use in white light applications. The effective properties of Dy3+/Eu3+ co-doped KFP glasses indicated that the present glasses might be useful for optical materials.