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Preparation And Properties Of White Light Phosphor With Apatite Structure For LED

Posted on:2020-06-29Degree:MasterType:Thesis
Country:ChinaCandidate:D D XuFull Text:PDF
GTID:2518306464986879Subject:Chemical Engineering
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White LED(WLED)has the advantages of energy saving,high safety factor and long life,and has attracted wide attention as the most promising new generation solid-state lighting source.Among them,the phosphor conversion WLED(pc-WLED)exhibits a huge advantage due to its low cost and simple preparation process.In recent years,apatite structure fluorescent materials have become an emerging material for phosphor conversion WLED research because of their physicochemical properties,low synthesis temperature and simple preparation method.In this paper,three new types of rare earth doped phosphors with apatite structure were prepared by high temperature solid phase method.The optical properties and luminescence mechanism were systematically studied,which provided a new idea for the research of WLED.(1)Sr4Ca(PO42(Si O4):Dy3+phosphor exhibits white light emission at 348 nm excitation due to the characteristic blue emission band(480 nm)and yellow light emission(574 nm)of Dy3+ions.In addition,by incorporating Li+,Na+or K+ions as charge compensators,the charge balance of the matrix and the symmetry of the crystal field were adjusted to study the effect on the luminescence properties.The results show that Sr4Ca(PO42(Si O4):Dy3+,M+(M=Li,Na,K)phosphors can be used as potential near-ultraviolet excitation white light-emitting diodes(w-LEDs).(2)Ba3La Na(PO43F:Tm3+,Dy3+phosphors have both Tm3+:1D2-3F4and Dy3+:4F9/2-6HJ(J=15/2,13/2,11/2)transitions at 358 nm excitation,thus showing white light emission.Due to the effective energy transfer(ET)from Tm3+to Dy3+ions,the luminescent color of the sample was found to change from blue to white.According to the illuminating emission intensity,the maximum energy transfer efficiency is calculated to be about 72.6%,and the Dy3+ions optimal doping concentration is 0.04.In addition,through the theoretical model of Dexter,the dipole-dipole interaction was confirmed to be the energy transfer mechanism from Tm3+to Dy3+ions.(3)Sr6Gd2Na2(PO46F2:Tb3+,Eu3+phosphors achieve the color-adjustable properties of phosphors by adjusting the concentration ratio of Tb3+-Eu3+ions at 371 nm excitation.By regulating the ratio of Tb3+/Eu3+,the modulation and optimization of the luminescence properties are achieved.In addition,the energy transfer process between Tb3+and Eu3+ions was studied,and the energy transfer mechanism of Sr6Gd2Na2(PO46F2:Tb3+,Eu3+was analyzed.The results show that Sr6Gd2Na2(PO46F2:Tb3+,Eu3+phosphors have potential applications in the field of pc-WLED.
Keywords/Search Tags:High temperature solid-state reaction, White LED, Apatite, Energy transfer
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