Study On Structure And Properties Of Eu²⁺ Doped Silicate Luminescent Materials

With the expanding market demand for lighting,rare earth phosphors for LEDs have become the focus of extensive research.With the advancement of technology,ultraviolet LEDs have been used in many fields due to their good lifetime,ease of use and portability.In this thesis,the luminescence properties of Eu2+in different silicate matrices were investigated with the aim of developing new phosphors that can be used in ultraviolet LEDs.The Mg₂SiO₄:xEu²⁺blue phosphors were prepared by secondary sintering using a high-temperature solid-phase method.When the primary calcination temperature was 1000?and the secondary calcination temperature was 1400?,it was the best synthesis temperature for the Mg₂SiO₄ substrate.The doping concentration was optimized and the best doping concentration was achieved when the doped Eu²⁺concentration was 0.1 mol%.The Mg₂SiO₄:0.001Eu²⁺phosphor sample is a promising blue-emitting phosphor under near-UV excitation conditions.The doping of Eu2+was selected as the concentration of 0.1 mol%to prepare Mg_2-xCa_xSiO4:0.001Eu²⁺phosphor samples.Under the excitation conditions of near-UV light,the samples are a promising green-emitting phosphor when Mg_2-xCa_xSiO4:0.001Eu²⁺phosphor x=0.25 and x=0.5;a promising blue-green-emitting phosphor when x=1;and a promising blue-emitting phosphor when x=1.5 and 2.The blue phosphors with Ca₃Mg(SiO₄)₂:xEu²⁺were prepared by using MgO,CaCO3,SiO2 and Eu2O3 as raw materials.By optimizing the doping concentration,the highest luminescence intensity of the samples was obtained when the doped Eu2+concentration was 0.5%,which proved that 0.5%mol was the best doping concentration.The Ca₃Mg(SiO₄)₂:0.05Eu²⁺phosphor is a promising blue luminescent phosphor under the excitation conditions of near-UV light.MgAl₂Si₄O₆N₄:xEu²⁺phosphor samples were prepared under a reducing atmosphere of 95%nitrogen and 5%hydrogen mixture.The pure phase of MgAl₂Si₄O₆N₄:xEu²⁺was obtained When the primary sintering temperature is1500? and the secondary sintering temperature is 1550?.The emission wavelength of the samples varied significantly with increasing doping concentration,showing a significant red shift.The best luminescence intensity of the samples was obtained when the doping concentration was 2 mol%.The MgAl₂Si₄O₆N₄:xEu²⁺phosphor sample is a promising blue-green luminescent phosphor under the excitation of near-UV light.