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

Abstract

The BaGd2–2xEu2xO4 (BG, x = 0.01–0.09) phosphors were successfully synthesized via the sol-gel method, and BaY2–2yEu2yO4 (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 BaGd1.9Eu0.1O4 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 BaGd1.9Eu0.1O4 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.