Synthesis and Photoluminescence Characteristics of High Color Purity and Brightness Li₃Ba₂Gd₃(MoO₄)₈:Eu³⁺ Red Phosphors

The object of this study is to synthesize Li 3 Ba 2 Gd 3 (MoO 4 ) 8 doped with Eu 3+ ions and prepared with solid-state reaction technology. The results show that the dominant emission peak of Li 3 Ba 2 Gd 3− x (MoO 4 ) 8:Eu x phosphor is 5 D 0 → 7 F 2 (614 nm). The intensity of the emission from 5 D 0 to 7 F 2 is 3.8 times higher than that of commercial phosphors, ZnS:(Mn 2+,Te 2+ ) when the Eu 3+ concentration is x = 2.4. The CIE chromaticity coordinates of the red emission of the Li 3 Ba 2 Gd 0.6 Eu 2.4 (MoO 4 ) 8 phosphor are (0.67, 0.33), which is the NTSC system standard for red chromaticity. Because there are two regions in the excitation spectra of Li 3 Ba 2 Gd 3 (MoO 4 ) 8:Eu 3+ phosphor, one is assigned from the charge-transfer state (CTS) band at about 320 nm, and the other is from the intra-4f transitions from 350 to 500 nm. Hence, the phosphors could be strongly excited by near-UV and blue LED in solid-state lighting technology. The analysis of the lifetime, decay curves, and efficiency of the 5 D 0 → 7 F 2 emission indicates the weak energy transfer between Eu 3+ pairs. The temperature dependence PL and absorption spectra study shows that thermal quenching behavior can be attributed to crossover from the 5 D 0 excited state to the CTS band.