新穎稀土激活氟磷酸鹽與氟矽酸鹽螢光體之製備與發光特性鑑定

Abstract

含氟的氟磷酸鹽及氟矽酸鹽化合物合成溫度普遍較低，製程容易、化學穩定性高。因此本論文主要探討可吸收近紫外光或藍光的稀土激活Ca2(Ba1-xEux)3(PO4)3F、(Ca1-xEux)4Si2O7F2、Ca2(Ba1-2xCexLix)3(PO4)3F、(Ca1-xCex)4Si2O7F2、Ca2(Ba0.99-yCe0.005Li0.005Euy)3(PO4)3F與(Ca0.998-yCe0.002Euy)- 4Si2O7F2等氟磷酸鹽及氟矽酸鹽螢光體之高溫固態合成、發光光譜與色度、熱消光與其在製作白光發光二極體之應用。本研究首先篩選激發頻寬為250∼400 nm的Eu2+或Ce3+為活化中心，進而調控Eu2+和Ce3+晶格格位之配位環境與晶場強度，達成最終調控螢光粉的發光波長的目標。 上述螢光粉須於還原氣氛中合成，本研究並利用X-光粉末繞射、掃描式電子顯微鏡、紫外-可見光光譜儀、激發、發射與瞬態螢光光譜、量子效率與色度座標分析進行螢光體之結構、發光特性及色度學特性分析鑑定，以了解其特徵與應用之潛力。 本論文第一部分探討不同主體之最佳製程條件與X光繞射晶相之分析鑑定；第二部分則探討Eu2+所摻雜主體之發光特性，並研究新穎螢光體之熱消光效應；第三部分則研究Ce3+摻雜螢光體之發光特性與熱消光效應，並針對摻雜離子取代格位環境與發光波長之關聯進行探討；第四部分則探討在Ca2Ba3(PO4)3F: Ce3+, Li+, Eu2+ and Ca4Si2O7F2: Ce3+, Eu2+螢光體中Ce3+與Eu2+間的能量轉移機制。 關鍵詞：螢光粉；發光二極體；氟磷酸鹽；氟矽酸鹽；能量轉移

In this study, we have successfully synthesized several novel phosphors with compositions of Ca2(Ba1-xEux)3(PO4)3F, (Ca1-xEux)4Si2O7F2, Ca2(Ba1-2x- CexLix)3(PO4)3F, (Ca1-xCex)4Si2O7F2, Ca2(Ba0.99-yCe0.005Li0.005Euy)3(PO4)3F, and (Ca0.998-yCe0.002Euy)4Si2O7F2 by using solid-state method under reducing H2/Ar atmosphere. The crystal structure, luminescence and chromaticity properties of these phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DR), and photoluminescence spectroscopy. This thesis first reports the optimization of synthetic condition for all phosphors and the analysis of XRD profiles. Then, the spectroscopic properties and thermal-quenching behaviors of Eu2+-doped phosphors were investigated, which were then rationalized by considering nephelauxetic effect and crystal field strength. Furthermore, the luminescence properties and thermal- quenching behaviors of Ce3+-activated phosphors have also been investigated. On the other hand, the Ce3+→Eu2+ energy transfer in systems of Ca2Ba3(PO4)3F: Ce3+, Li+, Eu2+ and Ca4Si2O7F2: Ce3+, Eu2+ were also studied and the energy transfer mechanisms were determined to be the dipole-dipole type interactions. Finally, this thesis discusses the results of all phosphors that we have synthesized and evaluates its applicability in the fabrication of white-LEDs.