發(fā)布時間：2018-05-26 03:44

  本文選題：微納晶體 + 上轉換　； 參考：《陜西師范大學》2015年博士論文

【摘要】：稀土離子由于其獨特的4f電子構型賦予了它譜線銳利、發(fā)射帶豐富、熒光壽命長、背景熒光低等諸多優(yōu)點,成為發(fā)光材料不可或缺的一部分。近年來,研究者成功地制備了各種各樣的稀土微納發(fā)光材料。由于稀土摻雜的微納發(fā)光材料在發(fā)光、固體激光器、生物學、納米光電子學、信息科學等領域均展現(xiàn)出巨大應用潛力,掀起了全球范圍內(nèi)新一輪的研究熱潮。本論文主要是以低聲子能量的微納氟化物基質(zhì)材料為研究對象,以熒光調(diào)控為主要研究目的,借助離子共摻雜技術實現(xiàn)發(fā)光離子熒光特性的有效調(diào)控,同時采用共焦顯微裝置對單顆粒的熒光特性進行了系統(tǒng)研究。主要工作和結論如下：(1)以LiYF4/NaYF4晶體為基質(zhì)材料,系統(tǒng)研究了Yb3+/Pr3+共摻LiYF4/NaYF4微米晶體及Yb3+/(Er3+, Tm3+, Ho3+, Ho3+/Tm3+)共摻LiYF4單顆粒的上轉換熒光特性,同時探討發(fā)光離子的熒光強度對Yb3+濃度的依賴關系。在近紅外光980nm激發(fā)下,隨著Yb3+濃度的增加,Pr3+在兩種基質(zhì)中均展現(xiàn)出赤眼可觀的熒光發(fā)射。Er3+,Tm3+, Ho3+, Ho3+/Tm3+在LiYF4單顆粒晶體中的發(fā)光強度及光譜顏色隨著Yb3+濃度增加也發(fā)生了明顯的變化。研究結果表明：增加Yb3+的摻雜濃度,可有效地改變發(fā)光離子的能級布居,增強離子之間的交叉弛豫幾率及濃度淬滅效應,從而導致光譜性質(zhì)變化。此外表面修飾劑EDTA對LiYF4微米顆粒的特性也有影響,加入EDTA不僅改變顆粒的形貌,而且降低顆粒發(fā)光效率,其原因主要是顆粒表面存在的EDTA有機配體增加無輻射躍遷幾率從而導致發(fā)光效率的降低。(2)以NaYF4晶體為基質(zhì)材料,系統(tǒng)研究了Yb3+/Ho3+共摻雜NaYF4納米晶及NaYF4單顆粒中Ho3+離子的上轉換熒光特性,同時對微米晶的形成及演化機理進行了系統(tǒng)研究。結果表明：通過共摻雜Ce3+實現(xiàn)了NaYF4納米晶中Ho3+的熒光發(fā)射從綠光向紅光轉變,其原因是由于Ce3+與Ho3+之間共振交叉弛豫過程增強紅光發(fā)射而淬滅綠光發(fā)射。通過動力學過程及對發(fā)光機理和能量轉移效率的分析研究,發(fā)現(xiàn)引入Ce3+不僅可有效調(diào)控Ho3+上轉換熒光發(fā)射峰的相對強度,而且在不改變基質(zhì)本身的情況下為獲得單一紅色熒光發(fā)射提供了新途徑。NaYF4:Yb3+/Ho3+單顆粒展現(xiàn)出很強糖果狀上轉換熒光發(fā)射圖案,并且其發(fā)射光譜隨著激發(fā)功率,顆粒數(shù)目及尺寸的不同而發(fā)生了明顯的變化,其原因是激發(fā)條件的變化導致了離子之間不同能量傳遞方式的產(chǎn)生。單顆粒發(fā)光特性的研究,有利于避免周圍環(huán)境對其的影響,同時可獲取更加精準的光譜信息,拓展單顆粒在微米發(fā)光器件中的應用前景。
[Abstract]:Due to its unique 4f electron configuration, rare earth ions have become an indispensable part of luminescent materials due to their sharp spectral lines, rich emission bands, long fluorescence lifetime and low background fluorescence. In recent years, researchers have successfully prepared various rare earth micro-nanoluminescence materials. Rare earth doped nanoluminescence materials have shown great application potential in the fields of luminescence, solid-state lasers, biology, nano-optoelectronics, information science and so on, which set off a new round of research upsurge in the world. In this thesis, we focus on the micro and nano fluorine matrix materials with low energy and fluorescence regulation as the main purpose, and realize the effective regulation of luminescent ion fluorescence characteristics by ion co-doping technology. At the same time, the fluorescence characteristics of single particle were studied by confocal microscopy. The main work and conclusions are as follows: (1) the up-conversion fluorescence properties of Yb3 / pr _ 3 co-doped LiYF4/NaYF4 microcrystals and Yb3 / er _ 3, Tm3, Ho3, Ho3 / TM ~ 3 codoped LiYF4 single particles were studied using LiYF4/NaYF4 crystal as substrate. The dependence of fluorescence intensity of luminescent ions on the concentration of Yb3 was also discussed. Excited by near-infrared 980nm, With the increase of Yb3 concentration, the luminescence intensity and spectral color of red eye fluorescence emission, Ho3 and Ho3 / TM 3 in LiYF4 single granular crystal also changed obviously with the increase of Yb3 concentration in both substrates. The results show that increasing the doping concentration of Yb3 can effectively change the energy level population of luminescent ions and enhance the cross-relaxation probability between ions and the concentration quenching effect resulting in the change of spectral properties. In addition, the surface modifier EDTA has an effect on the properties of LiYF4 micron particles. The addition of EDTA not only changes the morphology of the particles, but also reduces the luminescence efficiency of the particles. The main reason is that the existence of EDTA organic ligands on the surface of particles increases the probability of non-radiative transition, which results in the decrease of luminescence efficiency. The up-conversion fluorescence characteristics of Yb3 / Ho3 co-doped NaYF4 nanocrystals and Ho3 ions in single NaYF4 particles were systematically studied. The formation and evolution mechanism of micron crystals were also systematically studied. The results show that the fluorescence emission of Ho3 in NaYF4 nanocrystals can be transformed from green light to red light by co-doped Ce3. The reason is that the green emission is quenched because of the enhancement of red light emission due to the resonance cross-relaxation process between Ce3 and Ho3. Based on the kinetic process and the analysis of luminescence mechanism and energy transfer efficiency, it is found that the introduction of Ce3 can not only effectively regulate the relative intensity of upconversion fluorescence emission peak of Ho3. And without changing the substrate itself, it provides a new way to obtain a single red fluorescence emission. NaYF4: Yb3 / Ho3 single particle exhibits a very strong candy upconversion fluorescence emission pattern, and its emission spectrum is dependent on the excitation power. The number and size of particles change obviously because the change of excitation conditions leads to the generation of different energy transfer modes between ions. The study of single particle luminescence is beneficial to avoid the influence of surrounding environment on it, and to obtain more accurate spectral information, and to expand the application prospect of single particle in micron luminescent devices.
【學位授予單位】：陜西師范大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：O482.31
，

本文編號：1935810