本文選題：稀土離子　切入點(diǎn)：納米熒光材料　出處：《華中科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：稀土離子摻雜的無機(jī)熒光材料有不同顏色的發(fā)光,可以實(shí)現(xiàn)對(duì)光譜的轉(zhuǎn)換,因此,被用于多種領(lǐng)域�；谧贤夤獾娇梢姽獾南罗D(zhuǎn)換發(fā)光,稀土熒光粉可以用作LED顯示,光伏器件中的太陽光譜轉(zhuǎn)換層。借助于近紅外到可見光的上轉(zhuǎn)換發(fā)光,它們又能很好地用于固態(tài)激光器,三維立體成像和生物成像。當(dāng)前,國(guó)內(nèi)外有關(guān)稀土納米材料研究的熱點(diǎn)主要集中于兩方面:一是通過調(diào)控生長(zhǎng)條件或發(fā)明新的合成方法來控制納米晶體的尺寸,分散性和表面形貌;二是通過引入激活離子或者調(diào)節(jié)摻雜濃度來增強(qiáng)熒光效率。本文中,針對(duì)稀土離子躍遷基礎(chǔ)理論和實(shí)際應(yīng)用中存在的一些問題,開展了一系列有目的性的實(shí)驗(yàn),以下即是研究的三方面內(nèi)容:通過水熱合成法,對(duì)實(shí)驗(yàn)參數(shù)進(jìn)行合理地控制,我們制備出一系列具有中空球狀結(jié)構(gòu)的稀土摻雜釩酸鹽微/納米球樣品。研究發(fā)現(xiàn):反應(yīng)時(shí)間、酸堿度、添加劑檸檬酸(Cit3-)以及煅燒溫度等對(duì)樣品的最終結(jié)構(gòu)、表面形貌和晶粒尺寸產(chǎn)生了影響。其中,有機(jī)添加劑Cit3-一方面作為晶面生長(zhǎng)的導(dǎo)向劑,引導(dǎo)原始晶核沿著特定的[100]方向生長(zhǎng),進(jìn)而控制晶粒的形狀。另一方面,又可以重新分配納米顆粒表面能,進(jìn)而決定最終的顆粒分布以及表面形貌,協(xié)助中空球狀結(jié)構(gòu)的形成。同時(shí),我們提出了晶體的生長(zhǎng)機(jī)理。接下來我們研究了單摻雜Ln3+(Ln=Er、Eu、Dy、Ce、Ho、Yb)以及雙摻雜Ln3+-Yb3+(Ln=Er,Ho)釩酸鹽(YVO4)微/納米樣品的熒光性能。單摻雜的YVO4:Ln3+樣品可以通過VO43--Ln3+的能量傳遞,將紫外光轉(zhuǎn)化為可見光發(fā)射,并且可以發(fā)出多種顏色的光。此外,樣品表面缺陷、吸附物和晶粒尺寸的減小都會(huì)促進(jìn)熒光效率的提高。這種紫外光-可見光的光譜轉(zhuǎn)換可用于熒光顯示領(lǐng)域或者太陽能光伏領(lǐng)域,用來降低硅太陽能電池中熱損耗。在雙摻雜Er3+-Yb3+、Ho3+-Yb3+的釩酸釔(YVO4)樣品中,可以通過調(diào)整激發(fā)波長(zhǎng)獲得不同波段的上/下轉(zhuǎn)換發(fā)光。在上轉(zhuǎn)換過程中,Er3+/Ho3+-Yb3+樣品發(fā)射光譜中位于650nm處(Ho3+5F5→5I8;Er3+4F9/2→4I15/2)的紅色發(fā)光明顯增強(qiáng),而位于550nm處(Ho3+5S2,5F4→5I8;Er3+4S3/2→4I15/2)的綠色發(fā)光則受到抑制,這與紫外激發(fā)下的現(xiàn)象相反。結(jié)合熒光衰減曲線,我們系統(tǒng)地分析了上轉(zhuǎn)換和下轉(zhuǎn)換的發(fā)光過程,并提出了能量合作傳遞的機(jī)理。此外,發(fā)射光譜中紅/綠熒光的強(qiáng)度比值(R=IR/IG)可以通過改變摻雜濃度進(jìn)行調(diào)控。鑒于此,我們討論了其應(yīng)用于生物熒光探針、醫(yī)學(xué)成相和固態(tài)激光器的可能性。
[Abstract]:Rare earth ions doped inorganic fluorescent materials have different color luminescence, which can realize spectral conversion. Therefore, they are used in many fields. Based on the downconversion luminescence from ultraviolet to visible light, rare earth phosphors can be used as LED display. Solar spectral conversion layers in photovoltaic devices. With upconversion luminescence from near infrared to visible light, they can be well used in solid-state lasers, three-dimensional imaging and biological imaging. The research focuses on rare earth nanomaterials at home and abroad mainly focus on two aspects: one is to control the size, dispersity and surface morphology of nanocrystals by regulating growth conditions or inventing new synthesis methods; In this paper, aiming at some problems existing in the basic theory and practical application of rare earth ion transition, a series of purposeful experiments have been carried out. The following three aspects of the research are as follows: by hydrothermal synthesis, we prepared a series of rare earth doped vanadate microspheres with hollow spherical structure by reasonably controlling the experimental parameters. The final structure, surface morphology and grain size of the sample were affected by pH, citric acid citrate and calcination temperature, among which organic additive Cit3- was used as the orientation agent for crystal surface growth. Lead the original nucleus to grow along a specific [100] direction, and then control the shape of the grain. On the other hand, it is possible to redistribute the surface energy of the nanoparticles, which in turn determines the final particle distribution and surface morphology. Assist in the formation of hollow spherical structures. At the same time, We have proposed the growth mechanism of the crystal. Next, we have studied the fluorescence properties of mono-doped Ln3 (Ln3) and double doped Ln3 -Yb _ 3 (Ln ~ (3)) ~ (+) vanadate (YVO4). The single doped YVO4:Ln3 samples can transfer energy through VO43--Ln3. Convert ultraviolet light into visible light and emit light in a variety of colors. In addition, the surface of the sample is defective, The reduction of adsorbents and grain sizes will increase the efficiency of fluorescence. This conversion of ultraviolet to visible light can be used in the field of fluorescent display or solar photovoltaic. It is used to reduce the thermal loss in silicon solar cells. In the YVO4 / YVO4 sample of YVO _ 4 doped with Er3 -Yb _ 3 and Ho-Yb _ 3, The upconversion / downconversion luminescence of different wavelengths can be obtained by adjusting the excitation wavelength. The emission spectra of Er3 / Ho3 / Yb3 samples are located at 650 nm. 鈫，

本文編號(hào)：1607638