Preparation And Luminescence Properties Of BaY₂Si₃O₁₀:RE Phosphors

As the fourth generation light source, white LEDs have become one of the focus of researchers’attention due totheir many advantages, such as energy saving, environment friendly, small volume and long lifetime, et.al..White LEDs show wide market prospects. There are three main methods to realize the white LEDs:(a) Combination of a blue LED chip with yellow phosphor YAG:Ce3+; (b) Combination of tricolor LED chips; (c) Combination of UV LED chips with tricolor phosphors. Ultraviolet light is not sensitive to human’s eyes, so unlike the YAG:Ce3+ white LED, color quality of UV chip-based white LEDs is only decided by phosphors. UV chip-based white LEDs are considered as the next generation technology of white LEDs.This paper is aimed at studying on synthesis and luminescence properties of rare earth doped BaY2Si3O10 phosphors which can be excited by UV chips. The phosphors were synthesized by high temperature solid-state reaction, and their phase composition, crystal structures and luminescent properties were investigated carefully.(1) Blue phosphor BaY2Si3O10:Ce3+, Sm3+ was synthesized at 1623 K by the conventional solid-state method and systematically investigated by X-ray diffraction, photo-luminescence (PL) spectra. Excited by 330 nm ultraviolet light, the phosphors show an efficient blue wide-band emission with a peak in the range of 400-427 nm. The emission shows a red shift as increasing Ce3+ doping concentration. The concentration quenching was found to be governed by multipolar interactions. A significantly energy transfer of Ce3+â†'Sm3+ was also observed in BaY2Si3O10:Ce3+, Sm3+ phosphors. The luminous efficiency of Sm3+ can be improved by adjusting the Ce3+/Sm3+ proportion.(2) BaY2Si3O10 (BYSO):Ce3+, Tb3+ phosphors display tunable color emission from blue to blue-green under UV excitation by adjusting the radio of Ce3+ and Tb3+. The existence of efficient energy transfer from Ce3+ to Tb3+ in BaY2Si3O10:Ce3+, Tb3+ phosphor were demonstrated. The energy transfer Ce3+â†'Tb3+ was proved to be governed by dipole- quadrupole interaction. The phosphor has a strong and broad absorption band in the UV (260～350 nm), which is expected to be applied in UV based white LED and display field.(3) A series of BaY2Si3O10:Dy3+ and BaY2Si3O10:Ce3+, Dy3+ phosphors were synthesized by high temperature solid state reaction method and their spectral characteristics and Ce3+â†'Dy3+ energy transfer were studied.1 The emission spectrum of BaY2Si3O10:Dy3+ consists of two strong emission band with emission peaks at 486 nm and 571 nm, respectively, which belonging to 4F9/2-6H15/2 and 4F9/2-6H13/2 of the Dy3+ ions characteristic transitions. The concentration quenching of Dy3+ in BaY2Si3O10 host was demonstrated to be governed by electronic quadrupole-quadrupole interaction.Ce3+-Dy3+ energy transfer in BaY2Si3O10:Ce3+, Dy3+ phosphors was observed, and the doping of Ce3+ ions enhances the luminous efficiency and quenching concentration of Dy3+ significantly.