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Synthesis and Properties of Rare Earth Red-emitting Phosphors for White LED

Author: CongXiuHua
Tutor: WuQiuFang；GaoZuo
School: East China University of Science and Technology
Course: Chemical Engineering
Keywords: red phosphors molybdate light white LED
CLC: O482.31
Type: Master's thesis
Year: 2012
Downloads: 47
Quote: 0
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Abstract


A series of novel rare earth red light-emitting molybdate phosphors KCaY1-x(MoO4)3:Eux were synthesized in this work. The effect of the sintering temperature, holding time, concentration of Eu3+ and modification by optimizing process, adjusting substance component, utilizing sensitized ions on the properties of the red phosphors were studied in this paper.The experimental results show that KCaY1-x(MoO4)3:Eux(x=0.8) red phosphors synthesized by high temperature solid state reaction method under 950℃for 5 h have excellent properties. XRD patterns show that all the phosphors are isostructural, sharing a tetragonal scheelite structure with the space group I41/a(88). The excitation and emission wavelength show that these phosphors can be effectively excited by ultraviolet (394 nm) and blue (465 nm) light, emitting the maxium emission line at 613 nm with pure red light. The absorptions at the wavelengths of 394 nm and 465 nm are nicely fitting in with the widely applied emission wavelengths of ultraviolet or blue LED chips. So this red phosphors are promising candidates for solid-state lighting applications.The intensity of the phosphors can be enhanced by the method of secondary sintering, milling for raw materials and after-treatment for phosphors, the surface morphology and dispersion of the phosphors can also be improved by after-treatment. When introducing Si4+to adjust substance component, the emission intensity of the phosphors can be improved and the critical structure, surface morphology and emission spectra cannot be affected. The emission intensity of the phosphors synthesized under 1000℃and 10% mol of the concentration of Si4+ can be improved 1.72 times and 1.85 times under the excitation of 394 nm and 465 nm, respectively. When utilizing Bi3+ to sensitize Eu3+, the emission intensity of the phosphors can be improved and the critical structure, surface morphology and emission spectra also cannot be affected. The emission intensity of the phosphors synthesized under 900℃and 10% mol of the concentration of Bi3+ can be improved 1.22 times and 1.26 times under the excitation of 394 nm and 465 nm, respectively.

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CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Solid nature of the > Optical Properties > Luminescence
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