Judd–Ofelt parameters and X-ray irradiation results of MNb2O6:Eu3+ (M = Sr, Cd, Ni) phosphors synthesized via a molten salt method

Trivalent Eu-activated MNb2O6 (M = Sr, Cd, Ni) ceramic phosphors were produced using the molten salt route, which involves a low sintering temperature and provides improved homogeneity. The photoluminescence (PL) and radioluminescence (RL) spectra of phosphors exhibited characteristic Eu3+ emissions with 5F0 → 7F j transitions, and strong peaks occurred at the 5D0 → 7F2 transition. The PL and RL emissions of SrNb2O6:Eu3+ decreased over 3 mol%, while both emissions for CdNb2O6:Eu3+ and NiNb2O6:Eu3+ increased with increasing Eu3+ concentration. The spectral properties of phosphors were evaluated by determining Judd-Ofelt intensity parameters (Ω 2, Ω 4) from the PL emission spectrum. The quantum efficiencies (η QE%) of MNb2O6:Eu3+ (M = Sr, Cd, Ni) phosphors with the highest emission were found as 61.87%, 41.89%, and 11.87% respectively. Bandwidths (σ e × Δλ eff) and optical gains (σ e × τ) of MNb2O6:Eu3+ (M = Sr, Cd, Ni) phosphors with highest emissions were found as follows; 24.182 × 10-28, 28.674 × 10-28, 38.647 × 10-28 cm3 and 20.441 × 10-25, 13.790 × 10-25, 3.987 × 10-25 cm2 s, respectively, corresponding to the 5D0 → 7F2 transition.