一维金纳米粒子链的制备及其光学特性研究

在没有模板存在的条件下, 只用表面活性剂为稳定剂, 制备了一维的金纳米粒子链, 详细考察了链状结构形成时各种试剂浓度、种类及其它外部条件对纳米粒子链形成的影响. 实验发现, 在HAuCl₄ 浓度1～5 mmol•L^－1、十二烷基磺酸钠(SDS)浓度在2～8 mmol•L^－1 (小于其CMC)范围内, 温度由60 ℃ 0.5 h内升高到100 ℃, 并在升温时间内分次将还原剂加完, 反应完成后不老化立即冷却到室温, 可以获得一维金纳米粒子链. 采用紫外可见光谱(UV-Vis)、同步光散射光谱和发射光谱等手段对金纳米粒子链的光学特性进行了研究, 用高分辨透射电子显微镜(HRTEM)研究了金纳米粒子的外观和粒径分布, 结果表明制备的金纳米粒子链是错落有致的链状结构, 结节处可以观察到金原子的排列晶格, 说明金纳米粒子的链状连接不是外部分子作用的结果; 表面等离子体共振吸收峰出现红移现象, 且随着链长的增加红移越明显; 具有非常强的光散射特性, 散射光强度比浓度相同的金纳米粒子高8倍; 发射光谱中明显观察到其三级散射, 表明其具有很好的非线性光学特性. 对金纳米粒子链的形成机理进行了探讨, 认为表面活性剂烷基亲油作用和金原子的聚集作用相互竞争是链状结构形成的原因.     

CeF_3纳米粒子的制备和尺寸控制

利用萃取体系中形成的反胶团为微反应器制备了CeF_3纳米粒子.并对粒子尺寸进行了有效调控.结果表明,通过改变有机相浓度、料液以及反萃液的组成等,可以控制粒子的成核、生长和团聚,有效地对所制备的CeF_3纳米粒子尺寸进行调控.Triton X-100对CeF_3纳米粒子的分散存在一个转折浓度,即随着Triton X-100浓度增大,粉体团聚行为增强,当达到转折浓度时,粉体开始解聚,分散性变好.     

基础实验:金纳米粒子的制备及其光学性质

围绕金纳米粒子前沿内容,设计了一个简易的本科生基础实验,利用柠檬酸钠还原氯金酸法制备分散性好的金纳米粒子溶液,讨论了其尺寸与颜色的关系,探究了不同电解质和非电解质对金纳米粒子团聚及其颜色的影响,初步了解金纳米粒子的光学特性和探针效应基本原理。     

微波制备均分散氧化铁纳米粒子

微波制备均分散氧化铁纳米粒子汤勇铮杨红（皖南医学院生化组芜湖２４１００１）张文敏＊（安徽师范大学化学系芜湖２４１０００）关键词微波辐照纳米粒子α－Ｆｅ２Ｏ３三乙烯四胺（ＴＥＴＡ）均分散氧化铁胶体粒子有着广泛的应用［１］。可以用作制备催化剂、陶瓷、颜料...     

纳米ZnO的制备及其光学性质的研究

采用均匀沉淀法，以尿素与硝酸锌反应制备纳米ZnO，通过TG-DTA、XRD、IR及TEM等手段对纳米粒子及中间体进行了表征，结果表明制得的纳米粒子粒度均匀，粒径分布窄。对纳米ZnO的发光特性研究表明，随焙烧温度升高，粒度的增大，可见绿色发射增强。同时对纳米ZnO与普通ZnO的发光性质进行了比较研究，指出纳米ZnO的绿色发光带有蓝移现象，这是由于纳米ZnO的量子尺寸效应引起的。BET测试表明，纳米ZnO的比表面为171．2m^2／g，有利于作催化剂。     

均匀棒状β—FeOOH胶体粒子的制备研究

β—FeOOH是一种重要的含水铁氧化物,而能够控制大小的棒状胶体粒子的制备方法,又是获得优良磁记录材料的基础。Matijevic     

纳米粒子的性质

纳米粒子是近年来科学上的一项重大发现,已成为当今许多学科的研究热点之一。许多科技工作者对纳米粒子的性质进行了卓有成效的研究,本文仅就此予以论述。     

FeOOH明胶复合纳米粒子的制备与表征

采用两步法制备具有弱磁性的FeOOH纳米粒子和FeOOH明胶复合纳米粒子. 透射电镜、扫描电镜、红外光谱、X射线衍射和磁滞回线等测量结果表明: 在一定FeCl₃/Fe₂(SO₄)₃/H₂O摩尔比条件下, 加入十二烷基苯磺酸钠(ABS)溶液, 可制备粒径为30～150 nm弱磁性FeOOH纳米粒子, 其磁性可达6.5×10^－6 emu/g. 弱磁性FeOOH纳米粒子可被明胶包裹. 随着FeCl₃/Fe₂(SO₄)₃摩尔比减小或明胶浓度增加, 纳米球粒径增大, 磁性降低. 随着固化时间增加, FeOOH明胶复合纳米粒子的粒径先增大后减小.     

纳米粒子

纳米粒子，作为纳米材料科学中的重要一员，近年来一直受到科技界的广泛重视。本文拟从纳米粒子的情况、特性、制备方法及应用等方面，对其作综合评述，以期这一新材料能得以更为深入地研究和更广泛地应用。     

纳米粒子及其材料的特性、应用和制备

本文介绍了纳米粒子的一般概念、特性及本质根源。纳米粒子因其特异的性能在高科技领域得到了日益广泛的应用。文中对纳米材料现有的应用及其前景作了简要的介绍，并综合评述了目前国内外制备纳米粒子的常用方法，综述了引起粒子间团聚的机理和后处理过程中有效地防止团聚的方法。     

CdS nanoparticles chemically modified PAN functional materials: Preparation and nonlinear optical properties

The fabrication of nanocomposites by covalent inclusion of inorganic nanoparticles in an organic polymer matrix is highly topical and may find applications in the electronics, optics and energy sectors. Incorporation of CdS nanoparticles into the polyacrylonitrile (PAN) matrices could be expected to display improved or enhanced optoelectronic and optical properties. Using a newly synthesized RAFT agent, i.e., CdS-DDAT nanoparticles (DDAT: S-1-Dodecyl-S′-(α, α′-dimethyl-α′′-acetic acid) trithiocarbonate), CdS covalently functionalized polyacrylonitrile (CdS-PAN) nanocomposite material was prepared in the presence of small amount of AIBN under ultrasonic radiation. This material, which exhibits an induced positive nonlinear absorption of incident light, has been well-characterized by a variety of physical techniques such as GPC, UV/vis, FT-IR, TGA, XRD and Z-scan.     

Near monodisperse TiO2 nanoparticles and nanorods

Highly crystalline, near monodisperse TiO2 nanoparticles, nanorods and their metal-ion-doped (Sn4+, Fe3+, Co2+, and Ni2+, etc.) derivatives have been prepared by well-controlled solvothermal reactions. Through adjusting the reaction parameters, such as reaction temperature, duration, and concentration of the reactants, the size, shape, and dispersibility of the products can be controlled. A possible reaction mechanism can be proposed based on experimental evidence.     

水溶性CoFe2O4磁性纳米粒子的制备和磁性研究

采用溶剂热法,分别以FeCl3· 6H2O和CoCl2·4H20为铁源和钴源,二甘醇和二乙醇胺为溶剂和配位剂,制备了水溶性CoFe2O4纳米粒子.采用TEM、XRD、FTIR光谱、热重-差热分析等技术对所得纳米粒子进行表征,并研究了材料的磁学性质.结果表明,这种铁酸钴纳米粒子具有超顺磁性,饱和磁化强度M.达53.2em...     

Synthesis and optical properties of silver nanoparticles and arrays.

This Minireview systematically examines optical properties of silver nanoparticles as a function of size. Extinction, scattering, and absorption cross-sections and distance dependence of the local electromagnetic field, as well as the quadrupolar coupling of 2D assemblies of such particles are experimentally measured for a wide range of particle sizes. Such measurements were possible because of the development of a novel synthetic method for the size-controlled synthesis of chemically clean, highly crystalline silver nanoparticles of narrow size distribution. The method and its unique advantages are compared to other methods for synthesis of metal nanoparticles. Synthesis and properties of nanocomposite materials using these and other nanoparticles are also described. Important highlights in the history of the field of metal nanoparticles as well as an examination of the basic principles of plasmon resonances are included.     

Biocompatible NaYF4:Yb,Er upconversion nanoparticles: Colloidal stability and optical properties

Currently, highly luminescent colloidal upconversion nanoparticles (UCNPs) have expanded an increasing interest of researchers because of their facilitating lability in the biomedical/clinical field. In this study, NaYF₄:Yb,Er UCNPs are prepared by eco-friendly metal complexation-based thermal decomposition method at a lower temperature in aqueous media. The phase structure, crystallinity, phase purity, morphology, colloidal dispersibility, surface structure, surface charge, and optical and luminescent properties were evaluated carefully by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive x-ray analysis (EDX), Thermogravimetric analysis (TGA), zeta potential, Fourier transform infrared (FTIR), UV/visible and photoluminescent spectroscopic techniques. XRD pattern shows a pure single-phase cubic structure with an average grain size of 30–35 nm. TEM and SEM micrographs exhibited irregularly shaped spherical morphologies, porous surface structures highly aggregated UCNPs with the narrow-size distribution. Positive zeta potential has shown value signifying high absorption in the visible region which indicates particle's good colloidal stability in aqueous media. Under NIR-laser light excitation, the UCNPs emit strong UC emission transitions in the visible region. A broad infrared absorption peak of hydroxyl groups (–OH) in FTIR spectrum and mass loss at a lower temperature in TGA verified the surface functionality of UCNPs, with high colloidal stability, and excellent biocompatibility in aqueous media. In terms of their surface characteristics and high luminescent properties, the NaYF₄:Yb,Er UCNPs could be interestingly applied in tagging of biomolecules, drug delivery, proteins labeling, and therapeutic and thermostats applications.     

单分散磷酸镧纳米棒的可控制备

采用一步水热法在无模板情况下合成了单一形貌和尺寸均匀的磷酸镧纳米棒,产物分散性好.这种合成方法操作简单、能耗低、合成条件可控,并且重复性很好、可大面积合成.用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)对磷酸镧的形貌、结构以及相组成进行了分析.结果表明:所合成磷酸镧为单斜相独居石结构;纳米棒直径为15 nm,长度约为几百纳米,具有相当高的纵横比,有望在性能方面得到优化;磷酸镧纳米棒为单晶.对影响磷酸镧纳米棒形成的反应条件如水热温度和水热时间进行了研究,并详细研究了其生长过程.提出了磷酸镧纳米棒的可能生长机制是基于纳米颗粒的定向粘附作用.     

Preparation and nonlinear optical properties of two acrylate polymers bearing different long conjugated pendants

Two new acrylate monomers containing different long π-election conjugation bridge structure, 4′-[(N,N-diethylacrylate) amino], 4-(pyridine-4-vinyl) stilbene (DAS) and 4′-[(N,N-diethylacrylate) amino], 4-(pyridine-4-vinyl) azobenzene (DAA), were synthesized and their copolymers with methyl methacrylate (MMA) were prepared by free radical polymerization method. Their structures and properties of these copolymers were characterized and evaluated by FTIR, ¹H-NMR, UV spectra, GPC and Z-scan technique with 8 ns pulses at 532 nm wavelength. The relationship between their structures and properties was investigated. The results show that the structure of these resultant copolymers can be effectively tuned by simply varying the feed ratio and these copolymers exhibit good solubility and large third-order nonlinear optical properties. The large third-order nonlinear optical properties are mainly attributed to the substituted NLO-chromophore with long D-π-A conjugated structure. Simultaneously, it is found that poly (DAA-co-MMA) with N=N double bond as conjugation bridge has larger third-order nonlinear optical susceptibility than poly (DAS-co-MMA) with C=C double bond as conjugation bridge owing to more effective π electron conjugation effect.     

Cobalt nanoparticles in block copolymer micelles: Preparation and properties

 The preparation and properties of Co nanoparticles in polystyrene(PS)-poly-4-vinyl-py-ridine(PVP) micelles were studied. Elementary Co was generated by two methods: (i) by reduction of micelles loaded with CoCl₂, and (ii) by thermal decomposition of Co₂(CO)₈ in micel-lar solutions of such block copolymers. Co particles formed by both processes are effectively stabilized by the block copolymer matrix and do not aggregate. For CoCl₂ as a Co-source, the formed particles have a size less than 1 nm. Thermal treatment of such dried polymers at 200 ^°C for 2 h leads to spherical particles of 3–5 nm in size. The polymeric hybrid materials prepared in this way display remarkably high values of magnetization at rather low Co contents in the polymer, i.e., we obtain a tenfold increase of the specific magnetization density. Co₂(CO)₈ as a Co source, results in a more complex behavior. Co₂(CO)₈ dissolves in the solvent as well as in the micelle core where it is converted to an cationic–anionic complex involving the 4-VP units. The shape and size of the Co nanoparticles formed by thermolysis can be controlled by the balance of 4-VP/Co and can be varied from spherical particles in the limit of lower Co loads being mainly attached to the micelle core to a star-like and cubic morphology in case of excess of Co₂(CO)₈. Both superparamagnetic and ferromagnetic materials can be prepared. For ferromagnetic samples coercive force varies from 250 to 475 Oe depending on Co content and polymer sample. Received : 27 September 1996 Accepted: 22 November 1996     

Fe_3O_4/Au composite nano-particles and their optical properties

The colloid gold and magnetic particle modified with various chemical groups have been widely used in the areas of biomedical and molecular biology[1―6]. Therefore, a great deal of attention has been given to the preparation and application of colloid go…     

Preparation and properties of ionically cross‐linked chitosan nanoparticles

Chitosan nanoparticles were fabricated by a method of tripolyphosphate (TPP) cross‐linking. The influence of fabrication conditions on the physical properties and drug loading and release properties was investigated by transmission electron microscopy (TEM), dynamic light scattering (DLS), and UV–vis spectroscopy. The nanoparticles could be prepared only within a zone of appropriate chitosan and TPP concentrations. The particle size and surface zeta potential can be manipulated by variation of the fabrication conditions such as chitosan/TPP ratio and concentration, solution pH and salt addition. TEM observation revealed a core–shell structure for the as‐prepared nanoparticles, but a filled structure for the ciprofloxacin (CH) loaded particles. Results show that the chitosan nanoparticles were rather stable and no cytotoxicity of the chitosan nanoparticles was found in an in vitro cell culture experiment. Loading and release of CH can be modulated by the environmental factors such as solution pH and medium quality. Copyright © 2008 John Wiley & Sons, Ltd.