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Investigations on Energy-Saving Processes Preparing Phosphors by Seed Controled Growth and Thus Resulted Luminescence and Crystallinity
|Contributors: ||NTOU:Department of Marine Engineering|
SrTiO3:Pr;Al phosphors;nano-sized TiO2;core-shell structure;energy-saving microwave annealing
|Issue Date: ||2011-06-29T07:55:46Z
|Abstract: ||摘要:高解析度平面顯示器與LED螢光體的平均粒徑與結晶尺寸是極為重要關鍵。商用螢光體晶粒都在微米級以上，不只成本高且激發體積少，浪費其他未被激發的材料體積。欲提升發光效率則需提升激發能量或電壓，導致高發熱、高耗能；因此需要奈米級高發光效率的螢光體開發研究。然而減小螢光體結晶尺寸與減小一定晶粒大小的螢光粉體顆粒粒徑將大大降低其發光強度與效率。本計畫以環境友善的水熱法/溶劑熱法合成SrTiO3:Pr, Al螢光體，以奈米級TiO2晶種作用為水熱製程中螢光粉體的成核與成長助劑，利用限量奈米級晶種控制螢光體尺寸及結晶性，不需有機物或其他披覆層的表面披覆而能抑制結晶粒成長，並期望可限制後續熱處理之晶粒成長，維持高結晶性之高發光效率的奈米級螢光粉體。使用快速、潔能之微波退火製程進行結晶缺陷修飾、控制晶粒成長與促進激活劑的取代，更進一步得到不需表面缺陷補償與保護層而可提升螢光體之發光效率。本計畫將對核殼結構之溶解析出成長以及限制奈米晶粒成長與成核成長機制做深入研究。|
Abstract:The mean particle size and crystallite size of phosphors play an important role for the high resolution displays and LEDs. Commercial available phosphors must be micrometers scale at least, which is not cost-effective but low exciting volume for phosphor particle, so as to large part of particle volume without use in luminescence. High heat evolution and high energy consumption are resulted from high exciting energy for the increase of luminescent efficiency. Therefore, nanosized phosphors are necessary for high luminescent efficiency. However, phosphors with smaller crystallite size and smaller particle size at constant grain size will decrease the luminescent intensity and efficiency significantly. This study attempts to synthesize SrTiO3:Pr, Al phosphors using nano-sized TiO2 crystal seeds to control uniform shape, narrow particle size distribution, and well-crystallized phosphors with good luminescent characteristics. The resulted phosphors are without surface coating but exhibit good luminescent efficiency. Nano-seeds are used as nucleation and growth aids in hydrothermal/solvothermal method and to further limit the grain growth in post-annealing process. Microwave annealing method with rapid and energy-saving characteristics is used for modification of crystal defects and grain growth control as well as homogenizing activator distribution in phosphors. These results are expected to achieve high luminescent nano-phosphors without surface coating and protection layer. The mechanisms of dissolution-precipitaion in core-shell structure and of limited nucleation and grain growth to affecting crystallinity, size and shape of crystallite, microstructure, and cathodoluminescent properties for SrTiO3:Pr, Al phosphors will be explored in the study.
|Appears in Collections:||[輪機工程學系] 研究計畫|
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