臺灣博碩士論文加值系統

本論文旨在研究改變不同的摻雜濃度與製程溫度來合成Er3+-doped Y2Ti2O7粉末，並探討其螢光特性。

我們使用溶膠-凝膠法製備Er3+ (3, 5, 7, 10 mol%)-doped Y2Ti2O7奈米粉末，由實驗結果可得知其在Er3+ (5 mol%)–doped Y2Ti2O7粉末在退火溫度超過757℃後，具有良好的結晶特性，其平均結晶顆粒大小隨著退火溫度的提高 (800~1000 ℃) 而從~70 nm增加到~180 nm。在980 nm紅外線雷射激發下，具有下與上轉換發光特性，其發光峰值分別為526 nm (2H11/2→4I15/2 )、547 nm (4S3/2→4I15/2)、660 nm (4F9/2→4I15/2)、1528 nm ( 4I13/2→4I15/2)。

而螢光放射波長在1528 nm的螢光生命週期，在Er3+摻雜濃度為(5 mol%) 時其衰減曲線為單一指數，但摻雜濃度為10 mol%時就稍為有一點偏離單一指數，此兩種摻雜濃度其上轉換機制皆為雙光子吸收，但是Er3+摻雜濃度較高 (10 mol%) 時，則因為短的鉺離子間距進而增強了上轉換能量轉移(energy-transfer up-conversion)及交互緩弛能量轉移 (energy-transfer cross- relaxation) 機制，所以得到較強的紅光。

Er3+-doped Y2Ti2O7 nanocrystals were fabricated by the sol-gel method. While the annealing temperature exceeds 757 °C, amorphous pyrochlore phase Er3+-doped Y2Ti2O7 transfers to well-crystallized nanocrystals, and the average crystal size increases from ~70 to ~180 nm under 800 to 1000 °C/1 h annealing. The Er3+-doped Y2Ti2O7 nanocrystals absorbing the 980 nm photons can produce the up-conversion (526, 547, and 660 nm; 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2, respectively) and Stokes luminescence (1528 nm; 4I13/2→4I15/2).

The IR PL decay curve is single-exponential for Er3+ (5 mol%)-doped Y2Ti2O7 nanocrystals but slightly nonexponential for Er3+ (10 mol%)-doped Y2Ti2O7 nanocrystals. For both 5 and 10 mol% Er3+ doping concentrations, the mechanism of up-converted green light is the two-photon excited-state absorption; however, much stronger intensity of red light relative to green light was observed for sample with 10 mol% Er3+ doping concentration. This phenomenon can be attributed to the reduced distance between Er3+-Er3+ ions, resulting in the enhancement of the energy-transfer up-conversion and cross-relaxation mechanisms.

目錄
摘要………………………………………………………………………I
英文摘要………………………………………………………………II
致謝…………………………………………………………………..III
目錄…………………………………………………………………..IV
表目錄………………………………………………………………..VII
圖目錄……………………………………………………………….VIII
第一章 緒論...............................................1
1-1研究背景...............................................1
1-2 研究動機..............................................2
第二章 文獻回顧與理論基礎.................................4
2-1 發光機制簡介..........................................4
2-1-1 發光原理............................................4
2-1-2 螢光與磷光..........................................4
2-1-3 史托克位移..........................................5
2-1-4 波拉特選擇律........................................6
2-1-5 自旋選擇律..........................................6
2-2 螢光材料的分類與應用..................................7
2-2-1螢光材料的分類.......................................7
2-2-2螢光材料的應用.......................................9
2-3 稀土元素簡介.........................................10
2-3-1 稀土離子的電子躍遷.................................11
2-3-2 稀土離子的發光機制.................................11
2-4 影響螢光材料發光之因素...............................12
2-4-1 濃度粹取效應.......................................12
2-4-2 熱粹滅.............................................13
2-4-3 雜質毒化...........................................13
2-5 Y2Ti2O7螢光粉簡介....................................14
2-5-1 Pyrochlore結構特性介紹.............................14
2-5-2 Y2Ti2O7結構特性介紹................................15
2-6無機螢光材料之設計....................................15
2-7無機螢光材料之製備....................................16
2-7-1固態反應法..........................................16
2-7-2共同沉澱法..........................................17
2-7-3溶膠凝膠法..........................................17
第三章 實驗方法..........................................28
3-1 實驗藥品.............................................28
3-2 製程設備.............................................29
3-3 量測儀器.............................................29
3-3-1 掃瞄式電子顯微鏡...................................29
3-3-2 X-ray 粉末繞射分析.................................30
3-3-3 熱分析............................................30
3-3-4 光致發光光譜.......................................31
3-3-5 螢光生命週期.......................................32
3-4 實驗步驟.............................................33
第四章 結果與討論........................................38
4-1 熱重分析.............................................38
4-2 X-ray 粉末繞射分析...................................38
4-3掃瞄式電子顯微鏡分析..................................40
4-4光致發光光譜分析......................................41
4-4-1 全光譜分析.........................................41
4-4-2雷射功率對光譜強度之影響............................44
4-4-3 發光機制探討.......................................45
4-5螢光生命週期分析......................................47
第五章 結論與未來展望....................................60
參考文獻.................................................62

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