Synthesis and luminescent properties of BaGd2O4:Eu3+ phosphors with highly efficient red-emitting

The BaGd_2–2xEu_2xO₄ (BG, x = 0.01–0.09) phosphors were successfully synthesized via the sol-gel method, and BaY_2–2yEu_2yO₄ (BY, y = 0.005–0.07) phosphors were included for comparison. The pure phase BG phosphors with the ordered CaFe₂O₄-type structure are obtained by annealing at 1300 °C for 5 h. The phosphors with uniform particle size of 120 nm and good dispersion display typical Eu³⁺ emission with the strongest peak at 613 nm (⁵D₀→⁷F₂ transition of Eu³⁺) under optimal excitation band at 262 nm (CTB band). The presence of Gd³⁺ excitation bands on the PLE spectra monitoring the Eu³⁺ emission directly proves an evidence of Gd³⁺–Eu³⁺ energy transfer. Owing to the concentration quenching, the optimum content of Eu³⁺ addition is 5 at% (x = 0.05), and the quenching mechanism is determined to be the exchange reaction between Eu³⁺. All the BG samples have similar color coordinates and temperature of (0.64 ± 0.02, 0.36 ± 0.01) and 2000 ± 100 K, respectively. The lifetime value of BaGd_1.9Eu_0.1O₄ for 613 nm is fitted to be 2.19 ± 0.01 ms, and the Eu³⁺ concentration does not change the lifetime significantly. Owing to the Gd³⁺–Eu³⁺ energy transfer, the luminescent intensity of the BaGd_1.9Eu_0.1O₄ phosphor is better than BY system. The BG system served as a new type of phosphor is expected to be widely used in lighting and display areas.