臺灣博碩士論文加值系統

隨著綠色能源逐漸受到重視，使得照明領域中的白光LED受到廣泛的研究。然而，因白光LED仍受限於摻雜稀土元素之螢光粉末的高成本，導致無法大量普及。因此，本研究嘗試以鋁酸鍶材料進行無稀土元素的螢光粉之合成與開發。
本研究的鋁酸鍶材料之合成方式是採用高溫固相反應合成法，並藉著高速球磨混合，使得初始粉末能更均勻地混合。除了合成純Sr4Al14O25外，也試著合成摻雜有不同Mn4+濃度的樣品，透過XRD分析可發現到Mn4+的摻雜並未產生任何的雜相。利用PL分析發現到Mn4+的摻雜會顯著地提升原純相Sr4Al14O25所發出的652.7 nm的紅光亮度，而且其發光特徵峰並無明顯的位移。因此，也嘗試以不同的元素( Fe, Cr, V, Co, W)進行摻雜，並探討其發光特性的變化。
本研究除了藉由以第一原理來模擬計算，也配合各式光譜來探討Sr4Al14O25的能帶結構，並透過變溫光致螢光之分析，探討溫度對鋁酸鍶材料的發光特性的影響，並分別以費米-狄拉克分佈及Varshni 關係式探討其發光特性與溫度之關係，試圖更進一步地釐清產生紅色螢光及其螢光增強效應的機制。
由本研究結果顯示，無稀土元素摻雜的Sr4Al14O25螢光粉之開發是頗具潛力的，因為可藉由摻雜特定的過渡元素(Mn4+、Fe3+)來增強其螢光強度，並能降低其生產成本。

In response to the renewable and clear energy development, the white LED had been widely studied in the area of illumination. However, the rare earth-based white LED is expensive and thus it is difficult to become an increasingly popular lighting. One of the ways to solve the problems is the development of non-rare-earth emitting phosphors for LED. In this work, we report on a systematic study of the synthesis strontium aluminate phosphor and its red light-emitting mechanism.
The strontium aluminate materials were prepared by solid-state reactions in the study. The mixture was milled in a high energy ball mill to provide particles having substantially uniformly distributed. In addition to the synthesis of pure Sr4Al14O25, samples of different Mn doping contents were also prepared in the study. However, no impurity crystalline phase was detected for the Mn4+-doped Sr4Al14O25 samples. A characteristic 652.7 nm fluorescent peak of the sample are significantly enhancing in these Mn4+-doped specimens. However, no wavelength shift of emission peaks was found for these samples. To figure out the influence of different impurity on the emission peaks, a systematic doping with different transition metals or other elements (Fe、Cr、V、Co and W) were carried out.
With the hope to investigate the mechanism of red fluorescence and its enhancement effect, the band structure of strontium aluminate was proposed through the first-principles calculations. Data of temperature-dependent PL analysis on these samples can be fitted with the Varshni Equation and Fermi-Dirac distribution, and thus the relationship between temperature and luminescence properties were revealed.
The experimental results shows that the non-rare-earth-doped phosphors can be developed with a great potential, owing that the inexpensive transition metals (Mn4+, Fe3+) can significantly enhance the fluorescent intensity of Sr4Al14O25.

致謝　i
中文摘要　ii
Abstract　iii
目錄　v
圖次　vii
表次　ix
第一章　緒論　1
1-1　前言　1
1-2　研究動機　2
1-3　文獻回顧　3
第二章　量測原理及理論基礎　7
2-1　X光繞射(X-ray diffraction)原理　7
2-2　光致螢光光譜(Photoluminescence, PL)的原理　8
2-3　能帶理論　9
2-4　費米-狄拉克分佈(Fermi-Dirac distribution)　11
2-5　Varshni equation　13
第三章　實驗過程　14
3-1　實驗流程　14
3-2　樣品製備方法　15
3-3　分析方法與系統架構　17
3-3-1　X光繞射分析儀　17
3-3-2　光致螢光光譜儀　18
3-3-3　第一原理計算　20
第四章　結果與討論　21
4-1　未摻雜稀土元素之Sr4Al14O25分析　21
4-1-1　X光繞射分析　21
4-1-2　光致螢光分析　22
4-2　摻雜過渡元素之Sr4Al14O25分析　26
4-2-1　X光繞射分析　26
4-2-2　光致螢光分析　27
4-3　發光機制及其螢光增強效應分析　32
4-3-1　能帶結構與態密度分析　32
4-3-2　紫外線-可見光光譜分析　33
4-4　變溫光致螢光之發光特性分析　39
4-4-1　變溫之能隙分析　39
4-4-2　變溫之發光強度分析　41
第五章　結論　47
參考資料　48

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