The Structure And Luminescence Properties Of Rare Earth Ions Eu³⁺,Tb³⁺ Doped In BaSO₄-SiO₂ Phosphors

This paper adopts the method of sol-gel and precipitation, taking Ba(NO3)2, H2SO4 and Ethyl silicate as raw material to make BaSO4-SiO2:Eu3+, BaSO4-SiO2:Tb3+ and BaSO4-SiO2:Eu3+/Tb3+ phosphors, moreover, the crystals structure, morphology and luminescent properties of the phos phors were characterized and investigated by DTA –TG, XRD, IR, TEM, Uv-vis, excitation and emission spectra, respectively, studying the effect of the matrix ratioon, annealing temperature, doping concentration on lig ht-emitting material performance and focusing on the impact of SO42- co ntent on luminescence property and providing a detailed explanation.The Eu3+doped in BaSO4-SiO2 phosphors indicate that the samples exist mainly in the form of the bond of Si-O-Si, Ba-O and SO42- groups a nd BaSO4 exists in crystalline form after annealing at 600 ?. In addition, the best excitation wavelength was at 395 nm when the wavelength of the monitoring light was at 612 nm. With phosphors sintered at 800 ? and Eu doped with 9 mol% PL intensity geting maximum. Experiments found th at SO42- combining with Eu3+ will generate Eu2(SO4)3, and Eu3+ will occu py the position of Ba2+, affecting the luminescent properties of the materi als. The amount of SO42- can not change the structure of luminescent mat erials. The excitation and emission spectra show that SO42-can effectively improve the luminous intensity of luminescent materials when the a mou nt of SO42- just reached n(SO42-)=n(Ba2+)+3/2 n(Eu3+). The Ultravio let-V isible absorption spectrum demonstrates that SO42- is provided with strong ability to absorb ultraviolet light, and the energy levels of the excited stat e of SO42- and activator are in the effective transmission range, therefore, it can make energy transfer effectively to glowing ion, which is con duci ve to improving the luminous intensity. Finally, this text carries on the fu rther explanation and discussion about the energy transfer of SO42- combi ned with the theory of energy level.The Tb3+ doped Ba SO4-SiO2 phosphors indicate that the samples e xist mainly in the form of the bond of Si-O-Si, Ba-O and SO42- groups an d BaSO4 exists in crystalline form after annealing at 600 ?and the best e xcitation wavelength was at 543 nm with Tb doped 10 mol% PL intensity geting maximum. The effects of the amount of SO42- on the luminous int ensity were focused on. Luminous intensity is enhanced gradually when SO42- content is increased. SO42- and Tb3+ can be formed Tb2(SO4)3 due to e lectrostatic attraction.(Tb2(SO4)3)n form can be aggregated and solid-liqu id interface can be formed owing to strong hydrophobic force and interm olecular force, generating the system of(Tb2(SO4)3)n-Si O2 and producing a strong Rayleigh scattering peak, which is favor to luminescence. Exper imental results show that Tb3+doped Ba SO4-Si O2 phosphor can emit high intensity, good monochromaticity green light and can be excellent green l uminescent material.The BaSO4-SiO2 phosphors co-doped with Eu3+ and Tb3+ indicate t hat the white light emitting material can be possible synthesized due to ex iting in the red, green and blue band. When doped together, Tb3+ can sens itize Eu3+, the balance of Eu3+(4f6)+Tb3+(4f8)=Eu2+(4f7)+Tb4+(4f7) exists in the BaSO4-SiO2 phosphors doped with Eu3+and Tb3+, leading the mater ial to emit blue light of Eu2+, green light of Tb3+ and red light of Eu3+. Fi nally, white light emitting material is synthesized by adjusting the ratio of rare earth ions, and we will make it applicable as an efficient luminescen ce material for WLED.