Concentration dependent structural, optical and thermal investigations of Dy3+-doped sodium fluoroborate glasses

A new series of glasses (50−x)B2O3+20Na2O+20NaF+10La2O3+xDy2O3, where x=0.01, 0.1, 1, 2 and 3 have been prepared by conventional melt quenching technique. Structural, optical and thermal measurements of these Dy3+ doped sodium fluoroborate glasses were carried out and analyzed. The XRD pattern of the glasses confirmed the amorphous nature and the FTIR spectra reveal the presence of BO3 and BO4 units as their local structures along with the strong OH− groups. The absorption and luminescence spectral data have been used to calculate the Judd-Ofelt parameters, oscillator strengths, transition probability, branching ratio, etc. A strong yellow-blue emission is observed from the 4F9/2→6H13/2,15/2 transitions of Dy3+ ions and the peak emission stimulated cross-section (σPE) for the 4F9/2→6H13/2 transition is found to be comparable to the other reported Dy3+: glasses. The effect of composition on the intensity ratio of yellow to blue bands of Dy3+ ions has been studied. The lifetime of the 4F9/2 level has been measured and found to decrease with the increase in Dy3+ ion concentration. The DTA thermograms were recorded to study the thermal properties such as glass stability factor and Hruby's parameter of the prepared glasses and the results were discussed.