- 學位論文
溶液燃燒法製備摻雜銪之鹼土金屬鋁酸鹽螢光粉之合成與發光特性研究
Synthesis and Luminescent Properties of Europium-ion doped MAl2O4(M : Ca, Sr, Ba) Phosphors by Solution Combustion Method
摘要
本研究使用溶液燃燒法(solution combustion)合成無機螢光材料母體--鹼土金屬鋁酸鹽[MAl2O4（M： Ca、Sr、Ba）]，探討摻雜Eu的濃度對於製程條件相同的鹼土族鋁酸鹽之光學特性與晶格結構之影響。經還原燒成之Eu2+呈現出4f65d1 → 4f7躍遷之連續寬廣帶狀譜，且Eu在不同母體中，會呈現出不同顏色、強度與特性之放射光譜。實驗過程以XRD鑑定結晶相；以螢光光譜儀檢測螢光體之光激發特性；以SEM觀察表面形貌；以DTA 與TGA了解燒成製程條件。 實驗結果顯示，使用燃燒合成法能有效的縮短反應時間、獲得高純度產品以及均勻粒徑分佈。燃料比由低至高使前驅物產生三種不同的燃燒模式，分別為悶燃、自蔓反應以及體積燃燒反應，適當的燃料比會形成自蔓現象，即為最佳合成條件。在放射光譜量測結果顯示，MAl2O4：Eu2+（M： Ca、Sr、Ba）螢光粉的放射光譜以6P7/2→ 8S7/2的躍遷為主，但峰值位置受到主體晶格的共價性與晶體場分裂效應影響分別放出450 nm的藍光、520 nm與500 nm的綠光；MAl2O4：Eu3+（M：Ca、Sr）螢光粉的放射峰來自5D0→ 7FJ(J=1,2,3,4)躍遷，且放射光譜形狀不受主體晶格改變的影響，皆呈現橘紅光放射。 根據激發光譜分析，MAl2O4：Eu2+（M：Ca、Sr、Ba）及MAl2O4：Eu3+（M： Ca、Sr）螢光粉的激發波段均位於紫外光區域；故兩者以UV-LED激發可得紅、綠、藍三原色而混成白光，此型式轉換的白光涵蓋的波長範圍更接近自然光，具更高的演色性、光色均勻、無偏色現象等優點，在白光LED領域具有應用潛力。
並列摘要
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.