White light emission in Dy3+-doped lead fluorophosphate glasses

Lead fluorophosphate (PbFPDy: P2O5 + K2O + Al2O3 + PbF2 + Na2O + Dy2O3) glasses doped with different Dy3+ ion concentrations have been prepared and characterized through Raman, absorption, emission and decay rate measurements. Free-ion Hamiltonian model for energy level analysis and Judd–Ofelt theory for spectral intensities have been used to analyze the spectroscopic properties of Dy3+ ions in lead fluorophosphate glasses. The chromaticity coordinates were calculated from emission spectra and analyzed with Commission International de I’Eclairage color diagram and appear in the white light region under ultraviolet excitation. The decay rates for 4F9/2 level have been measured and are found to be deviated from exponential to non-exponential nature with increase in Dy3+ ion concentration. The non-exponential decay rates have been fitted with the Inokuti–Hirayama model for S = 6, which revealed that dipole–dipole mechanism is responsible for the energy transfer processes through Dy3+–Dy3+ interaction.