發(fā)布時(shí)間：2018-08-05 13:03

【摘要】：發(fā)光材料在現(xiàn)代生活當(dāng)中扮演著至關(guān)重要的角色,稀土發(fā)光材料作為發(fā)光材料中的重要一部分被廣泛的應(yīng)用于熒光探測分析、燈光照明系統(tǒng)和醫(yī)用影像檢測等各個(gè)領(lǐng)域。其中的鈮酸鹽功能材料不僅擁有優(yōu)良的化學(xué)和熱穩(wěn)定性,同時(shí)還在壓電和非線性光學(xué)方面具有良好的性質(zhì),成為一種很重要的發(fā)光基質(zhì)材料。目前,通常用來合成鈮酸鹽粉體的方法主要是高溫固相反應(yīng)法,這種方法的優(yōu)點(diǎn)就是過程比較簡單,適合于大規(guī)模的生產(chǎn),但反應(yīng)過程能量需求大,反應(yīng)所需時(shí)間比較長,而且產(chǎn)物離子分布不均勻,容易混入雜質(zhì)。熔鹽合成技術(shù)以其合成溫度低、產(chǎn)物形貌可控、設(shè)備簡單等優(yōu)勢近年來在材料合成領(lǐng)域得到廣泛應(yīng)用。本論文采用熔鹽法合成K2LaNb5O15粉體,系統(tǒng)的通過改變?nèi)埯}用量,煅燒溫度,保溫時(shí)間以及不同熔鹽體系等條件來研究K2LaNb5O15粉體的晶體結(jié)構(gòu)和形貌,分析了熔鹽法合成K2LaNb5O15粉體的反應(yīng)機(jī)理,最終確定了最佳的制備工藝流程;研究了K2LaNb5O15粉體及摻雜不同稀土離子的K2LaNb5O15:Ln3+(Ln3+=Eu3+,Tb3+)熒光粉的發(fā)光特性及發(fā)光機(jī)理,主要研究內(nèi)容如下:1、以氧化鑭、氧化鈮、氯化鉀和硫酸鉀為原料,采用熔鹽法制備了K2LaNb5O15粉體,探討了熔鹽用量、煅燒溫度、保溫時(shí)間以及不同熔鹽體系等對K2LaNb5O15粉體的晶體結(jié)構(gòu)和微觀形貌的影響。研究結(jié)果表明,合成K2LaNb5O15粉體的最佳熔鹽配比是KCl實(shí)際/KCl理論=7.5:1此時(shí)產(chǎn)物為鎢青銅結(jié)構(gòu),形貌比較均勻,呈長10um、直徑1um的棒狀結(jié)構(gòu);KCl在770℃時(shí)融化,K2LaNb5O15開始結(jié)晶,隨著溫度的升高,K2LaNb5O15粉體的結(jié)晶度相應(yīng)提高,K2LaNb5O15粉體的最佳焙燒溫度是1000℃,此時(shí)結(jié)晶完全,粉體形貌為均勻的棒狀;保溫時(shí)間為2h和3h時(shí),合成的樣品形貌均勻性最好,為長度集中在10um、直徑1um的棒狀結(jié)構(gòu)。采用KCl做單一熔鹽時(shí),制備的樣品的微觀形貌基本都是較細(xì)長的棒狀,形貌比較均勻和規(guī)整。隨著熔鹽中K2SO4的增加,樣品的形貌均勻性變差,短柱狀顆粒增多。2、通過在K2LaNb5O15基質(zhì)中摻雜不同稀土離子Ln3+(Eu3+,Tb3+),合成了具有層狀鎢青銅結(jié)構(gòu)的K2LaNb5O15:Ln3+熒光粉,并且使用用熒光光譜儀測定了基質(zhì)K2LaNb5O15粉體和K2LaNb5O15:Ln3+粉體的激發(fā)和發(fā)射光譜,并分析了其發(fā)光機(jī)理。結(jié)果表明,K2LaNb5O15粉體自身具有很強(qiáng)的藍(lán)光發(fā)射,屬于自激活基質(zhì)發(fā)光。K2LaNb5O15:Ln3+熒光粉的激發(fā)-發(fā)射光譜是由基質(zhì)的譜帶和稀土離子自身f-f特征躍遷譜線兩部分所構(gòu)成,說明K2LaNb5O15和稀土離子之間存在著能量傳遞關(guān)系。
[Abstract]:Luminescent materials play an important role in modern life. As an important part of luminescent materials, rare earth luminescent materials are widely used in various fields, such as fluorescence detection and analysis, lighting systems and medical image detection. The niobate functional materials not only have excellent chemical and thermal stability, but also have good properties in piezoelectric and nonlinear optics. At present, the main method used to synthesize niobate powder is the high temperature solid state reaction method. The advantage of this method is that the process is relatively simple and suitable for large-scale production, but the reaction process requires a large amount of energy and takes a long time to react. Moreover, the ion distribution of the product is not uniform, and it is easy to be mixed with impurities. Molten salt synthesis technology has been widely used in the field of material synthesis in recent years because of its low synthesis temperature, controllable product morphology, simple equipment and so on. In this paper, K2LaNb5O15 powder was synthesized by molten salt method. The crystal structure and morphology of K2LaNb5O15 powder were studied by changing the amount of molten salt, calcining temperature, holding time and different molten salt system. The reaction mechanism of K2LaNb5O15 powder synthesized by molten salt method was analyzed, and the optimum preparation process was determined, and the luminescence characteristics and mechanism of K2LaNb5O15 powder and K2LaNb5O15:Ln3 (Ln3 EU 3 EU 3 Tb 3) phosphor doped with different rare earth ions were studied. The main research contents are as follows: K2LaNb5O15 powder was prepared by molten salt method with lanthanum oxide, niobium oxide, potassium chloride and potassium sulfate as raw materials. The amount of molten salt and calcination temperature were discussed. The effects of holding time and different molten salt systems on the crystal structure and microstructure of K2LaNb5O15 powders were investigated. The results show that the optimum ratio of molten salt to synthesized K2LaNb5O15 powder is that the product of KCl's actual / KCl theory of 7.5: 1 is tungsten bronze with a uniform morphology and a long length of 10 um.The rod-like structure of 1um melts KCl at 770 鈩，

本文編號(hào)：2165880