【摘要】：材料的可控制備以及性能的優(yōu)化是納米材料能夠?qū)崿F(xiàn)實際應用的必要條件。相對于常見的納秒激光,長脈寬毫秒激光液相燒蝕法能夠提供穩(wěn)定的生長條件、具備較高的制備效率,通過改變液體介質(zhì)種類、激光參數(shù)等條件有望控制納米材料的形貌、尺寸、結(jié)構(gòu)組成和表面狀態(tài)等,對于優(yōu)化納米材料的制備工藝、實現(xiàn)材料的可控合成具有非常重要的意義。 硅及氧化鋅是一種環(huán)境友好的熒光納米材料,近年來受到了科研工作者廣泛的關(guān)注。本課題重點研究了硅基及氧化鋅基納米材料的制備及光學性能。利用毫秒激光液相燒蝕法,改變靶材成分、組成,液相介質(zhì)種類,激光參數(shù),制備得到了多種新型的納米結(jié)構(gòu)。 通過激光燒蝕誘導一氧化硅的相分離,首次得到了形狀規(guī)則的球狀納米晶。對比不同激光參數(shù)和不同溶液中的作用結(jié)果,提出硅納米球的生長機制,指出硅納米球是在激光誘導產(chǎn)生的低溫固相區(qū)形成的,激光瞬間產(chǎn)生的極高的溫度和極快的冷卻速度是形成納米球的關(guān)鍵。本課題還通過激光燒蝕硅氧碳,得到了含有碳化硅納米球的復合結(jié)構(gòu)。 通過激光燒蝕有機物溶液中的硅納米球,能夠顯著改善硅納米球的分散性。增大激光單脈沖能量,能夠得到石墨層包覆的硅納米球。激光燒蝕正己烷中的硅靶,能夠直接得到碳化硅、碳包硅基納米材料等多種材料。有機物在激光誘導高溫下能夠發(fā)生分解,產(chǎn)生碳原子,吸附在硅晶表面形成碳層或與直接參與納米晶的形成過程,得到多種結(jié)構(gòu)的納米晶。 通過激光燒蝕復合靶材,制備得到分散良好、尺寸均勻、穩(wěn)定性高、水溶的摻雜氧化鋅納米晶。利用化學置換法得到混合均勻的銅鋅靶,改變靶材的銅鋅比例,可以得到不同摻雜度的銅摻雜氧化鋅納米晶。由于銅在氧化鋅中形成了新的受主能級,納米晶的熒光隨摻雜濃度的升高不斷產(chǎn)生紅移。本課題通過改變靶材的成分,還得到了錳摻雜、鎂摻雜、鋰摻雜的氧化鋅納米晶。 通過化學沉淀法,得到了大量的氧化鋅納米晶。改變原料比例,得到了具有不同的發(fā)光性能的氧化鋅納米晶,分析認為不同的發(fā)光源自于不同的缺陷。通過不同的胺類有機物修飾影響了氧化鋅的熒光性能�？偨Y(jié)了有機物的影響機制,認為缺陷的種類以及有機物如何與缺陷相作用是決定有機物修飾后熒光強度升高或降低的關(guān)鍵。
[Abstract]:Controllable preparation and optimization of properties are the necessary conditions for nanomaterials to be applied in practice. Compared with the conventional nanosecond laser, the long pulse width millisecond laser ablation method can provide stable growth conditions and high preparation efficiency. By changing the type of liquid medium, laser parameters and other conditions are expected to control the morphology of nanomaterials. The size, structure composition and surface state are very important for optimizing the preparation process of nanomaterials and realizing the controllable synthesis of materials. Silicon and zinc oxide are environmentally friendly fluorescent nanomaterials, which have attracted extensive attention of researchers in recent years. The preparation and optical properties of silicon-based and zinc oxide-based nanomaterials were studied. A variety of novel nanostructures were prepared by millisecond laser liquid phase ablation by changing the composition and composition of the target material, the type of liquid medium and the laser parameters. The spherical nanocrystals with regular shape were obtained by laser ablation induced phase separation of silicon oxide. The growth mechanism of silicon nanospheres was put forward by comparing the results of different laser parameters and different solutions. It was pointed out that silicon nanospheres were formed in the low temperature solid region induced by laser. The key to the formation of nanospheres is the extremely high temperature and rapid cooling rate generated by the laser. The composite structure of silicon carbide nanospheres was obtained by laser ablation of silicon oxide carbon. The dispersion of silicon nanospheres can be improved by laser ablation of silicon nanospheres in organic solution. The graphite coated silicon nanospheres can be obtained by increasing the laser single pulse energy. Laser ablation of silicon targets in n-hexane can directly obtain silicon carbide, carbon encapsulated silicon based nanomaterials and other materials. Organic matter can be decomposed at high temperature induced by laser to produce carbon atoms and adsorb on the surface of silicon crystal to form carbon layer or directly participate in the formation process of nanocrystalline. A variety of nanocrystalline structures can be obtained. Doped ZnO nanocrystals with good dispersion, uniform size, high stability and water solubility were prepared by laser ablation. The copper-zinc oxide nanocrystalline with different doping degree can be obtained by chemical substitution method. As copper forms a new acceptor level in zinc oxide, the fluorescence of nanocrystals is redshift with the increase of doping concentration. By changing the composition of the target, manganese doped, magnesium doped and lithium doped ZnO nanocrystals were obtained. A large number of ZnO nanocrystals were obtained by chemical precipitation method. The ZnO nanocrystals with different luminescence properties were obtained by changing the ratio of raw materials. The results show that the different luminescence originates from different defects. The fluorescence properties of zinc oxide were affected by different amines. The influence mechanism of organic compounds is summarized. It is concluded that the types of defects and how organic compounds interact with defects are the key factors to determine the increase or decrease of fluorescence intensity after modification of organic compounds.
【學位授予單位】：天津大學
【學位級別】：博士
【學位授予年份】：2010
【分類號】：TB383.1

【共引文獻】

相關(guān)博士學位論文 前3條

1 劉東光;納米結(jié)構(gòu)碳氮基薄膜的設計與機械性能[D];浙江大學;2011年

2 牛凱陽;毫秒脈沖激光可控合成納米結(jié)構(gòu)[D];天津大學;2011年

3 趙元春;碳/碳氮一維納米材料的制備、物性以及相關(guān)器件的研究[D];中國科學院研究生院（國家納米科學中心）;2008年

相關(guān)碩士學位論文 前1條

1 呂奎明;利用毫秒脈沖激光合成新型納米結(jié)構(gòu)[D];天津大學;2009年

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本文編號：2256608