Preparation And Luminescence Properties Of Ce³⁺,Eu²⁺ Doped Several Typical Luminescence Materials For White LED Application

White LED has gradually replaced traditional lighting sources to become the fourth generation lighting source due to its advantages of energy saving,environmental friendliness,high efficiency,harmless and long service life et al.The dominating technique in the international market to obtain white light output is the phosphor conversion:blue chip?450-470 nm?stimulates phosphor to emit visible light?yellow,green+red?,which combine with the remaining blue light to obtain white light.However,the above implementation scheme has problems such as insufficient red components in yellow phosphors,scarcity of efficient green phosphors,and scarcity of phosphors directly applicable to AC LEDs.In view of the above main problems,the research was carried out from the following aspects:1.Introducing N^3-/O^2-?67%?anionic substitution into the lattice of Li₂SrSiO₄:Eu²⁺,a denser oxynitride luminescence material Li₂SrSiON₂:Eu²⁺was obtained.With the increase of Eu²⁺?x?concentration,luminescence intensity increased and reached a maximum at x=0.02,while the position of emission peak did not changed obviously.Under the excitation of 450 nm,The optimal sample Li₂SrSiON₂:0.02Eu²⁺emits bright orange emission peaking at 586 nm with sufficient red component and a wide full-width at half-maximum?110 nm?.Its emission intensity can reach 80%of commercial YAG:Ce³⁺under 450 nm excitation.2.By introducing various[Si⁴⁺+N^3-]ion pairs into Ca₂BO₃Cl:Eu²⁺lattice to replace[B³⁺+O^2-],color tunable and thermal stable luminescence materials Ca_1.96B_1-ySi_yO_3-yN_yCl:Eu²⁺_0.04.04 were successfully synthesized.With the increase of y value,blue-shifts of emission peaks from 582?y=0?to 525 nm?y=0.2?were observed,while the luminescence intensity and FWHM did not changed significantly.The measured FWHM values are 125,127,124,and 128 nm correspond to y=0,0.1,0.15,and 0.2,respectively.Compared with commercial BaSi₂O₂N₂:Eu²⁺?cyan?and?Ba,Sr?₂SiO₄:Eu²⁺?green?,the FWHM of the optimal sample CBSOCN_0.2:0.04Eu²⁺is significantly larger than them,and its emission intensity can reach 86%of BaSi₂O₂N₂:Eu²⁺and 93%of?Ba,Sr?₂SiO₄:Eu²⁺.3.Silicate phosphor Ba₂SiO₄:Eu²⁺?excited by UV/NUV?was chosen as target.By introducing a small amount of[Al³⁺+Al³⁺]?[Si⁴⁺+Si⁴⁺+O^2-]co-substitution into lattice,the luminescence properties were tuned.When y over 0.2,the excitation spectrum expanded to the blue light zone,and can matched with the blue light chip.Moreover,the decreased Stokes shift benefit to the thermal stability.The normalized spectral comparison between the optimal sample Ba_1.98(Si_0.8Al_0.2)O_3.9:Eu²⁺_0.02,commercial?-sialon:Eu²⁺and SrSi₂O₂N₂:Eu²⁺indicated that emission spectrum of Ba_1.98(Si_0.8Al_0.2)O_3.9:Eu²⁺_0.02.02 was significantly wider and has strong emission in the cyan region?470-510 nm?.4.Short persistence phosphor Gd₃Al₃Ga₂O₁₂:Ce³⁺was chosen as target.By introducing[Si⁴⁺+N^3-]?[Al³⁺+O^2-]bi-substitution into its lattice,solid solution phosphors Gd₃Ga₂(Al_3-ySi_y)(O_12-yN_y):Ce³⁺were synthesized.With the increase of y value,red-shift of emission spectra and expansion of FWHM were induced.So that the modified luminescent material Gd_2.95Ga₂Al_2.5Si_0.5O_11.5N_0.5:Ce³⁺not only can combined with blue light chip,but also contained sufficient red component.Meanwhile,when removed the excitation source,10 ms persistence luminescence behaviors were detected.Above results make it has potential application in warm white AC-LEDs.