The de-clustering influence of aluminum ions on the emission features of Nd3+ ions in PbO–SiO2 glasses

Nd3+ doped lead alumino silicate glasses with varying concentration of Al2O3 (from 5 to 10 mol%) have been synthesized. The IR and Raman spectral studies of these glasses have indicated that there is a gradual increase in the depolymerization of the glass network with increase in the concentration of Al2O3. The optical absorption, luminescence spectra and fluorescence decay curves of these glasses were recorded at room temperature. From these studies, the radiative parameters viz., spontaneous emission probability A, the total emission probability, the radiative lifetime τ, the fluorescent branching ratio β of different transitions originated from 4F3/2 level of Nd3+ ions have been evaluated. A clear increase in the quantum efficiency and luminescence emission of the two prominent NIR bands of Nd3+ ions viz., 4F3/2→4I11/2, 13/2, is observed with increase in the concentration of Al2O3. The increase has been attributed to the possible admixing of wavefunctions of opposite parities and due to the declusterization of Nd3+ ions by Al3+ ions in the glass network.