A Study on the Synthesis and Luminescence of Novel Halometalborate and Germanate phosphors for White-Light Emitting Diodes
|摘要:||本研究利用固態合成法於還原氣氛中成功合成BaAlBO3F2:Ln (Ln = Ce3+，Eu2+)、 Ba2AlB4O9Cl: Ln (Ln = Ce3+) 、Ba2GaB4O9Cl: Ln (Ln = Ce3+ , Eu2+)與Sr3(MO4)F: Ce3+ (M = Al，Ga) 四系列與 Na2AGe6O14: Mn 4+ (A= Ca，Sr)等螢光體，並利用紫外-可見光全反射光譜、X-ray 粉末繞射、螢光光譜、量子效率與色度座標分析以進行上述螢光體之晶相結構、發光特性及色度學座標之分析鑑定，其主旨在於開發新穎且具有應用價值之螢光體。
本論文第一部分探討不同主體之最佳合成條件與X光繞射晶相之分析鑑定；第二部分探討Ce3+摻雜不同主體之發光特性，並針對摻雜離子取代格位環境與放光波長的關聯性作進一步之探討；第三部分則探討BaAlBO3F2:Ce3+，Tb3+中Ce3+與Tb3+間的能量轉移機制；第四部分探討Eu2+摻雜不同主體之發光特性，並針對放光波長與摻雜離子格位配位環境的關係作進一步之探討；第五部分則探討摻雜Mn 4+之Na2AGe6O14: Mn 4+ (A= Ca，Sr)激發與放光光譜；第六部分探討上述螢光體之熱消光效應，以作為螢光二極體應用之參考。|
On this study, we have successfully synthesized several novel phosphors with compositions of BaAlBO3F2:Ln (Ln = Ce3+, Eu2+) , Ba2AlB4O9Cl: Ln (Ln = Ce3 ) , Ba2GaB4O9Cl: Ln (Ln = Ce3+ , Eu2+) , Sr3(AlO4)F: Ce3+ and Sr3(GaO4)F: Ce3+ by using solid-state method under H2/Ar reduction atmosphere and phosphors of Na2MGe6O14: Mn 4+ (M=Ca , Sr) by using solid-state method in the air. The crystal structure , luminescence and chromaticity properties of these phosphors were characterized by diffuse reflectance spectroscopy (DR), X-ray diffraction (XRD) and photoluminescence spectroscopy. This research is divided into six chapters. We first report the optimization of synthetic condition for all phosphors and the analysis of XRD profiles. We then investigated the spectroscopic properties of Ce3+- doped phosphors and the correlation between dopant sites and the emission wavelength. Furthermore , the Ce3+→ Tb3+ energy transfer in the BaAlBO3F2 : Ce3+, Tb3+ system was also studied and the energy transfer mechanism has been determined to be dipole-diple type interaction. On the other hand , the luminescence properties of Eu2+ -activated BaAlBO3F2 and Ba2MB4O9Cl (M=Al , Ga) have also been investigated , which were rationalized by considering covalency effect and crystal field strength. Red emitting Mn4+ - activated Na2MGe6O14: Mn 4+ (M=Ca , Sr) were also studied. Finally , the thermal-quenching behaviors for all phosphors were investigated for evaluating theis potential application in the fabrication of white LEDs.