Synthesis, crystal structure and photoluminescence properties of novel Ba3Lu4O9:Ce3+ orange-red phosphors for white light emitting diodes

Abstract

The exploration of red phosphors is very meaningful for enhancing the color rendering index (CRI) of white-light-emitting diodes (WLEDs). Herein, the novel BLO:Ce3+ orange-red phosphors are successfully synthesized by the high-temperature solid-state reaction via introducing Ce3+ ions into the Ba3Lu4O9 host. Structural analysis shows there was only the BLO:Ce3+ phosphors in the obtained product according to the standard diffraction card. The optimal preparation condition is the single-pass sintering in H2 at 1873 K for 3 h. In the spectral aspect, the optimal Ce3+-doped concentration is 0.5 atom %, and the strongest excitation and emission peaks of are located at 410 nm and 584 nm, respectively. Compared to reported Ba3Sc4O9:Ce3+ phosphors, the emission peak of BLO:Ce3+ phosphors is effectively red-shifted to about 21 nm. The fluorescent lifetime of BLO:Ce3+ phosphors is about 11.45 ns. Based on the temperature-dependent spectral and structural investigations, the thermal fluorescent quenching of BLO:Ce3+ phosphors originates mainly from the surrounding change of Ce3+ ions, and it is more evident at the temperatures below 340 K. Moreover, the crystallographic sites of the Ce3+ ions in Ba3Lu4O9 are also verified according to the temperature-dependent photoluminescence characterization with the excitation of 355 nm and empirical theoretical analysis, suggesting the observed luminescence mainly comes from the Ce3+ ions located in the LuO6 and BaO6 polyhedra. Finally, utilizing the as-prepared BLO:Ce3+ phosphors, commercial green phosphors and a blue LED, the WLED device is fabricated with a warm white-light performance in the color rendering (Ra = 91.2 and R9 = 88) and color temperature (3758 K) aspects. This study indicates the potential application of BLO:Ce3+ orange-red phosphors in the white-light illumination, and also provides some guiding inspirations in the exploration new red oxide phosphors.