毫秒激光液相烧蚀法制备荧光纳米材料及表面修饰的研究
发布时间：2018-10-08 11:41
【摘要】：材料的可控制备以及性能的优化是纳米材料能够实现实际应用的必要条件。相对于常见的纳秒激光,长脉宽毫秒激光液相烧蚀法能够提供稳定的生长条件、具备较高的制备效率,通过改变液体介质种类、激光参数等条件有望控制纳米材料的形貌、尺寸、结构组成和表面状态等,对于优化纳米材料的制备工艺、实现材料的可控合成具有非常重要的意义。 硅及氧化锌是一种环境友好的荧光纳米材料,近年来受到了科研工作者广泛的关注。本课题重点研究了硅基及氧化锌基纳米材料的制备及光学性能。利用毫秒激光液相烧蚀法,改变靶材成分、组成,液相介质种类,激光参数,制备得到了多种新型的纳米结构。 通过激光烧蚀诱导一氧化硅的相分离,首次得到了形状规则的球状纳米晶。对比不同激光参数和不同溶液中的作用结果,提出硅纳米球的生长机制,指出硅纳米球是在激光诱导产生的低温固相区形成的,激光瞬间产生的极高的温度和极快的冷却速度是形成纳米球的关键。本课题还通过激光烧蚀硅氧碳,得到了含有碳化硅纳米球的复合结构。 通过激光烧蚀有机物溶液中的硅纳米球,能够显著改善硅纳米球的分散性。增大激光单脉冲能量,能够得到石墨层包覆的硅纳米球。激光烧蚀正己烷中的硅靶,能够直接得到碳化硅、碳包硅基纳米材料等多种材料。有机物在激光诱导高温下能够发生分解,产生碳原子,吸附在硅晶表面形成碳层或与直接参与纳米晶的形成过程,得到多种结构的纳米晶。 通过激光烧蚀复合靶材,制备得到分散良好、尺寸均匀、稳定性高、水溶的掺杂氧化锌纳米晶。利用化学置换法得到混合均匀的铜锌靶,改变靶材的铜锌比例,可以得到不同掺杂度的铜掺杂氧化锌纳米晶。由于铜在氧化锌中形成了新的受主能级,纳米晶的荧光随掺杂浓度的升高不断产生红移。本课题通过改变靶材的成分,还得到了锰掺杂、镁掺杂、锂掺杂的氧化锌纳米晶。 通过化学沉淀法,得到了大量的氧化锌纳米晶。改变原料比例,得到了具有不同的发光性能的氧化锌纳米晶,分析认为不同的发光源自于不同的缺陷。通过不同的胺类有机物修饰影响了氧化锌的荧光性能。总结了有机物的影响机制,认为缺陷的种类以及有机物如何与缺陷相作用是决定有机物修饰后荧光强度升高或降低的关键。
[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.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：TB383.1
本文编号：2256608
[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.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：TB383.1
【共引文献】
相关博士学位论文 前3条
1 刘东光;纳米结构碳氮基薄膜的设计与机械性能[D];浙江大学;2011年
2 牛凯阳;毫秒脉冲激光可控合成纳米结构[D];天津大学;2011年
3 赵元春;碳/碳氮一维纳米材料的制备、物性以及相关器件的研究[D];中国科学院研究生院（国家纳米科学中心）;2008年
相关硕士学位论文 前1条
1 吕奎明;利用毫秒脉冲激光合成新型纳米结构[D];天津大学;2009年
，本文编号：2256608
本文链接：https://www.wllwen.com/shekelunwen/minzhuminquanlunwen/2256608.html
