Emission Enhancement of Eu3+ Ions in LiY(PO3)(4) Phosphate Phosphors via Anionic SO4 (2-) Substitution

摘要

Eu3+-doped LiY(PO3)(4(1-x))(SO4)(4x) (LYSO:Eu) phosphors are synthesized by high-temperature solid-phase method. The crystal structure, microscopic morphology and photo-spectrographic characteristics are analyzed respectively. The phosphor exhibits the strongest excitation peak at 397 nm, which indicates that the sample can be effectively excited by the near-ultraviolet/ultraviolet LED chip. The characteristic emission peaks of Eu3+ ion D-5(0) RARR;F-7(J) (J = 0, 1, 2, 3, 4) are observed from the PL spectrum, and the orange emission peak originating from the magnetic dipole transition D-5(0) RARR;F-7(1) of Eu3+ is located near 597 nm. When the SO4 (2-) concentration exceeds 22.5 mol, the quenching of the phosphor occurs. The Eu3+ emission still retains 78.8 of the initial strength at 495 K, with excellent thermal stability. The emission intensity is decreased with the increase of SO4 (2-) concentration, indicating that the SO4 (2-) co-doping leads to an increase in the probability of non-radiative transitions. The best quantum efficiency of the LiY0.95(PO3)(2.6)(SO4)(1.4): 0.05Eu(3+) sample is 86.65, and the CIE chromaticity coordinates of this sample are (0.653, 0.347), which are close to the international standard red color coordinates (0.67, 0.33). These results indicate that LYSO:Eu has a good application in NUV/UV excited white LEDs. Influence of anionic substitutions of SO4 (2-) on the optical properties is discussed.