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

Abstract

The object of this study is to synthesize Li3Ba2Gd3(MoO4)8 doped with Eu3+ ions and prepared with solid-state reaction technology. The results show that the dominant emission peak of Li3Ba2Gd3−x(MoO4)8:Eux phosphor is 5D0 → 7F2 (614 nm). The intensity of the emission from 5D0 to 7F2 is 3.8 times higher than that of commercial phosphors, ZnS:(Mn2+,Te2+) when the Eu3+ concentration is x = 2.4. The CIE chromaticity coordinates of the red emission of the Li3Ba2Gd0.6Eu2.4(MoO4)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 Li3Ba2Gd3(MoO4)8:Eu3+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 5D0 → 7F2 emission indicates the weak energy transfer between Eu3+ pairs. The temperature dependence PL and absorption spectra study shows that thermal quenching behavior can be attributed to crossover from the 5D0 excited state to the CTS band.