White light emission from Dy3+ doped sodium–lead borophosphate glasses under UV light excitation

• In this study we prepared SLBP glasses doped with Dy3+ ions.
• Glasses are characterized with FTIR, optical absorption and emission analysis.
• Judd–Ofelt theory is used to calculate radiative and fluorescence properties.
• The decay rate of the 4F9/2 level exhibits bi-exponential nature in studied glasses.
• The quantum efficiency for the 4F9/2 level is found to be 95%.

Sodium–lead borophosphate glasses doped with different Dy3+ concentrations have been prepared and characterized through, XRD, FTIR, optical absorption and photoluminescence techniques. FTIR spectrum indicates the presence of BO3 and PO4 structural units. The optical absorption spectrum has been studied at room temperature and several bands have been observed. These bands have been assigned to the ground state 6H15/2 to several excited states. The bonding parameters have been evaluated based on the observed band positions. From the absorption spectrum, Judd–Ofelt (J–O) intensity parameters have been evaluated. By using J–O parameters radiative parameters such as transition probabilities, branching ratios and absorption cross section have been evaluated. The emission spectra have been studied for different concentrations of Dy3+ ions. The yellow/blue values due to 4F9/2 → 6H13/2/4F9/2 → 6H15/2 luminescence intensity ratios of Dy3+ ions, increase with increasing concentrations, suggesting higher asymmetry and more covalent bonding character between Dy and oxygen ligands. The chromaticity coordinates were calculated from emission spectra and analysed with Commission International deI’Eclarige Color diagram. The life time of the 4F9/2 level has been measured and found to decrease with increase in Dy3+ ions concentration.