Optical absorption and photoluminescence properties of Nd3+ doped mixed alkali phosphate glasses-spectroscopic investigations

Spectroscopic investigations were performed on 68NH4H2PO4·xLi2CO3(30 − x)K2CO3 and 68NH4H2PO4·xNa2CO3(30 − x)K2CO3 (where x = 5, 10, 15, 20 and 25) glasses containing 2 mol% Nd2O3. Various spectroscopic parameters (Racah (E1, E2, E3), spin–orbit (ξ4f) and configuration interaction (α)) are reported. Judd–Ofelt intensity parameters (Ω2, Ω4, Ω6) are calculated for Nd3+ doped two mixed alkali phosphate glass matrices. From the magnitude of Judd–Ofelt parameters, covalency is studied as a function of x in the glass matrix. Using Judd–Ofelt intensity parameters, total radiative transition probabilities (AT), radiative lifetimes (τR), branching ratios (β) and integrated absorption cross sections (Σ) have been computed for certain excited states of Nd3+ in these mixed alkali phosphate glasses. Emission cross sections (σP) are calculated for the two transitions, 4G7/2 → 4I11/2 and 4G7/2 → 4I13/2 of Nd3+ in these mixed alkali phosphate glasses. Optical band gaps (Eopt) for direct and indirect transitions are reported.