本文選題：水熱法 + 上轉(zhuǎn)換納米晶��； 參考：《昆明理工大學(xué)》2017年碩士論文

【摘要】：在上轉(zhuǎn)換納米材料中,由于稀土離子的摻雜以及其本身具有較高的比表面積,晶體中缺陷的存在是不可避免的。人們對(duì)于納米材料缺陷態(tài)的研究偏重于如何修飾晶體表面的缺陷而忽略關(guān)于內(nèi)部缺陷態(tài)應(yīng)用的研究。本文通過(guò)加入不同表面活性劑、改變制備條件以及摻雜其他稀土離子和金屬離子制備了KLu2F7和KLu3F10上轉(zhuǎn)換納米晶,并對(duì)樣品的晶體缺陷態(tài)、結(jié)構(gòu)形貌以及光學(xué)性能進(jìn)行了深入研究。本文的研究工作主要為以下幾部分:1.缺陷態(tài)對(duì)光子協(xié)同效應(yīng)的促進(jìn)作用。通過(guò)應(yīng)用紫外和近紅外光作為光源共同激發(fā)Yb3+/Er3+共摻KLu2F7納米晶,觀察到了光子協(xié)同效應(yīng)和“光子類(lèi)雪崩”現(xiàn)象,并且通過(guò)調(diào)節(jié)反應(yīng)條件以及稀土離子摻雜量對(duì)光子協(xié)同效應(yīng)進(jìn)行了有效的增強(qiáng)。通過(guò)10 mol%Ce3+離子的摻雜可以引入淺陷阱或者作為橋梁將深陷阱轉(zhuǎn)化為淺陷阱,從而提高淺陷阱的密度并降低深陷阱的密度。結(jié)果表明,淺陷阱有助于增強(qiáng)光子協(xié)同效應(yīng),深陷阱會(huì)促進(jìn)“光子類(lèi)雪崩”現(xiàn)象的發(fā)生。由上轉(zhuǎn)換和下轉(zhuǎn)換合作的光致發(fā)光機(jī)理以及缺陷態(tài)的協(xié)助作用可知,光子協(xié)同增強(qiáng)效應(yīng)通過(guò)以下三個(gè)途徑產(chǎn)生:“熱損失”能量的再利用;亞穩(wěn)態(tài)能級(jí)電子的再激發(fā)和缺陷俘獲電子的釋放。2.Li+離子摻雜對(duì)上轉(zhuǎn)換發(fā)光的增強(qiáng)作用。通過(guò)摻雜半徑較小的Li+離子作為電荷補(bǔ)償劑,可以有效降低KLu2F7:Yb3+/Er3+納米顆粒中缺陷態(tài)的密度,進(jìn)而增強(qiáng)上轉(zhuǎn)換發(fā)光強(qiáng)度。結(jié)果表明,Li+離子的最佳摻雜濃度為10 mol%,與未摻雜樣品相比增大了 12倍。隨著980 nm激發(fā)功率密度的增加,最佳摻雜樣品的發(fā)光顏色由黃色變?yōu)榫G色。3.表面活性劑對(duì)上轉(zhuǎn)換發(fā)光性能的影響。表面活性劑CTAB可以通過(guò)對(duì)Yb3+/Er3+摻雜KLuF10納米晶的表面修飾作用,降低表面缺陷態(tài)密度增強(qiáng)上轉(zhuǎn)換發(fā)光強(qiáng)度。并且表面活性劑CTAB和油酸的加入可以調(diào)控Yb3+/Er3+,Yb3+/Ho3+,Yb3+/Tm3+摻雜樣品的上轉(zhuǎn)換發(fā)光強(qiáng)度以及發(fā)光顏色,最終得到紅綠藍(lán)三基色上轉(zhuǎn)換發(fā)光以及近紅外發(fā)光,這為納米顆粒在生物成像中的應(yīng)用提供了新思路。綜上所述,上轉(zhuǎn)換納米晶中缺陷態(tài)結(jié)構(gòu)的探索對(duì)其性能研究至關(guān)重要,通過(guò)調(diào)控缺陷態(tài)結(jié)構(gòu)可以改善其上轉(zhuǎn)換發(fā)光性能,為上轉(zhuǎn)換納米晶在太陽(yáng)能電池以及生物醫(yī)學(xué)等方向的應(yīng)用提供了新思路。
[Abstract]:Due to the doping of rare earth ions and its high specific surface area in up-conversion nanomaterials, the existence of defects in crystals is inevitable. The research on the defect states of nanomaterials is focused on how to modify the defects on the crystal surface, but the application of the internal defect states is neglected. In this paper, KLu2F7 and KLu3F10 up-conversion nanocrystals were prepared by adding different surfactants, changing the preparation conditions and doping other rare earth ions and metal ions. The crystal defect states, morphology and optical properties of the samples were studied. The research work of this paper is as follows: 1. The effect of defect state on photon synergy. By using ultraviolet and near-infrared light as light sources to excite Yb3 / er _ 3 co-doped KLu2F7 nanocrystals, the photon synergistic effect and "photon avalanche" phenomenon are observed. The photon synergy was enhanced by adjusting the reaction conditions and doping amount of rare earth ions. By doping 10 mol 3 ions, shallow traps can be introduced or converted into shallow traps as a bridge, thus increasing the density of shallow traps and reducing the density of deep traps. The results show that shallow traps are helpful to enhance photon synergy, and deep traps can promote the occurrence of photon avalanche. From the photoluminescence mechanism of up-conversion and downconversion cooperation and the assistance of defect states, we can see that the photon synergistic enhancement effect is produced through the following three ways: the reuse of "heat loss" energy; Reexcitation of metastable level electrons and release of defect capture electrons. 2.Enhancement of up-conversion luminescence by Li ion doping. By doping Li ion with small radius as charge compensator, the density of defect states in KLu2F7:Yb3 / er _ 3 nanoparticles can be reduced effectively, and the intensity of up-conversion luminescence can be enhanced. The results show that the optimum doping concentration of Li ion is 10 mol / L, which is 12 times higher than that of the undoped sample. With the increase of excitation power density at 980 nm, the luminescence color of the best doped sample changed from yellow to green. 3. Effect of surfactant on upconversion luminescence. The surface modification of Yb3 / Er3 doped KLuF10 nanocrystals by surfactant CTAB can reduce the density of surface defect states and enhance the up-conversion luminescence intensity. The addition of surfactant CTAB and oleic acid can control the up-conversion luminescence intensity and luminescence color of Yb3 / Er3 / Ho3 / Yb3 / TM ~ 3 doped sample. Finally, red, green and blue trichromatic up-conversion luminescence and near-infrared luminescence can be obtained. This provides a new idea for the application of nanoparticles in biological imaging. In conclusion, the exploration of defect state structure in up-conversion nanocrystalline is very important to the study of its properties, and the up-conversion luminescence property can be improved by regulating the defect state structure. It provides a new idea for the application of up-conversion nanocrystals in solar cells and biomedicine.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TQ422;TB383.1

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本文編號(hào)：1814201