Synthesis and Luminescent Properties of Europium-ion doped MAl2O4(M : Ca, Sr, Ba) Phosphors by Solution Combustion Method

• Main Authors: Jyun-Ye Hu, 胡俊業
• Other Authors: Kai-Hung Hsu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/yx5dtn

碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 99 === 　　This study aimed to prepare MAl2O4（M = Ca, Sr, Ba）by solution combustion method. The impact of the doping concentration of Eu on the luminescence and lattice structure was examined. The 4f65d1 → 4f7 spectrum of Eu2+ fired in reduced atmosphere was continuous and broad. Depending on host lattices, various colors, intensity and characteristic of emission spectrum were recognized. Analyzing instruments like X-ray diffractometer (XRD), fluorescence spectrometer, and scanning electron microscope (SEM) were utilized to analyze the crystallinity, the phosphorescence characteristic, and the surface structure, respectively. Furthermore, with help of differential thermal (DTA) / thermogravimetry analyzer (TGA), conditions for firing process were explained. 　　It was experimentally confirmed the reaction time could be effectively reduced by adopting solution combustion method. The product showed high purity and homogeneous distribution of particle size. As the Glycine/Metal nitrate(G/M) ratio increased, three different combustion modes - volumetric, self-propagating, and smothering combustion - occurred respectively. An appropriate G/M ratio resulted in SHS phenomenon, so that it was identified as the optimized synthesis condition. MAl2O4:Eu2+(M = Ca, Sr, Ba) phosphors showed a 6P7/2→ 8S7/2 transition with bluish 450 nm, greenish 520 nm and 500 nm emission. This phenomenon resulted from the covalence and crystal field splitting effects of the host lattice. In contrast, the emission peaks of MAl2O4:Eu3+(M = Ca, Sr) phosphors were originated from 5D0→ 7FJ(J=1,2,3,4) transition, which showed an orange-red color. Variation of host lattices did not play a critical role in this process. 　　According to excitation spectra, the main excitation peaks of MAl2O4:Eu2+(M = Ca, Sr, Ba) and MAl2O4:Eu3+(M = Ca, Sr) phosphors are located at ultraviolet region. Stimulated by UV-LED, both of them could absorb the UV wave band red, green, and the blue three kind of phosphor way blending with white light. The white light generated by such conversion covered a wavelength range closer to that of the natural light. Owing to higher color rendering property, higher light color uniformity, and absence of color deviation, these phosphors have high application potential for the white light LED industry.