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Synthesis of YAG: Ce Phosphor Powders

Author: JiaNaiTao
Tutor: ZhangXuDong
School: Shandong Institute of Light Industry
Course: Materials Science
Keywords: White light-emitting diodes Spherical phosphor Yttrium aluminum garnet Rare earths
CLC: TN104.3
Type: Master's thesis
Year: 2009
Downloads: 314
Quote: 1
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Abstract


Cerium-doped yttrium aluminum garnet phosphor as key materials prepared white LED has an important impact on the quality of the luminance white LED life indicators. Preparation of rare earth yttrium aluminum garnet phosphor calcination method solid phase, liquid phase co-precipitation, sol - gel method, combustion method, solid-phase method and become the production process is simple, and cost advantages of Yttrium aluminum garnet phosphor. Using the coprecipitation method, with ammonium bicarbonate as the precipitating agent, the mixed solution reaction and nitrate obtained YAG: Ce precursor, and the precursor was calcined at different temperatures under. YAG: Ce precursor and calcined powders were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) technology. The results show that the obtained was calcined at 1 100 ℃ YAG precursor, undoped YAG crystal phase, YAP, YAM mesophase appears, XRD, TEM, and specific surface area analysis shows that in the grain diameter of 1 100 ℃ calcining the resulting powder was 40 - 80 nm, with better dispersion. In this paper, the composite Solvothermal low cost YAG powders were prepared. Can be synthesized under the conditions under the conditions of ammonium bicarbonate as the precipitating agent, the obtained precursor powder were incubated for 5 h at 200 ℃ average grain size of 100-160 nm, good dispersibility, and having a spherical morphology pure phase YAG powder. YAG: Ce phosphor was prepared on the basis of research on the the YAG powder synthesis process using ethylenediamine and ethanol composite Solvothermal. The results show that: the precursor after precipitation by alcohol wash, without being dried directly solvothermal reaction, and incubated under the conditions of 15 h at 210 ℃ can be synthesized having a spherical morphology of pure phase YAG: Ce phosphor. Fluorescence spectroscopy, YAG: Ce phosphor excitation spectra for the double-peak structure, a weak peak at 340 nm in the near UV maximum excitation peak at around 450 nm, belonging Ce 3 4f → 5d Feature transitions. The emission spectrum is a peak at 530 nm, a broadband, corresponding to a of Ce 3 5d → 4f transition. And when the the sample emission peak at 530 nm, the emission spectra yellow-green, for a broadband-like spectrum. Therefore, a YAG: CE issued yellow light can be a good match with the Blu mixed to form white light. On the basis of the above study, this paper discusses the solvent synthesis YAG: Ce reaction mechanism. Finally, we study the YAG: Ce powder preparation process of polymer additives powder phase, morphology and luminescence properties of. Experimental selection, polyethylene glycol, gum arabic, and polyvinyl alcohol as an additive. The experiments show that the polyethylene glycol YAG: Ce powder particle size range between 20-30 nm, dispersion, luminescent properties. Not only can be used as a phosphor LED lights, but also because of its smaller particle size, good application prospects in the fluorescent labeling.

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