| Popis: |
Sodium–lead borophosphate glasses doped with different Dy 3+ concentrations have been prepared and characterized through, XRD, FTIR, optical absorption and photoluminescence techniques. FTIR spectrum indicates the presence of BO 3 and PO 4 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 6 H 15/2 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 Dy 3+ ions. The yellow/blue values due to 4 F 9/2 → 6 H 13/2 / 4 F 9/2 → 6 H 15/2 luminescence intensity ratios of Dy 3+ 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 4 F 9/2 level has been measured and found to decrease with increase in Dy 3+ ions concentration. |
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