关键词： 银纳米立方颗粒   核壳结构   微区光谱   上转换发光  

摘要： 采用化学还原法一步合成银纳米立方颗粒,并利用St?ber法制备了Ag@Si O_2纳米核壳结构,通过改变正硅酸乙酯(TEOS)加入量可调节Si O_2壳层厚度(7.5~33.0 nm)。样品吸收光谱表明,Ag@Si O_2纳米颗粒的偶极共振吸收峰相对于Ag纳米立方颗粒明显红移,但Si O_2壳层厚度对银纳米立方颗粒的共振吸收峰位影响不大。将Ag或Ag@Si O_2纳米颗粒掺入Na YF_4:Er^(3+),Yb^(3+)上转换纳米发光材料,通过微区荧光光谱研究了单个Ag或Ag@Si O_2纳米颗粒对周围Na YF_4:Er^(3+),Yb^(3+)上转换发光的等离子体增强。测得单个Ag@Si O_2纳米颗粒对红光和绿光上转换的增强因子分别为2.7和1.5,而单个Ag纳米颗粒只对绿光有增强。表明该纳米复合材料在太阳能电池及生物检测有着潜在的应用。

关键词： 溶剂热法   气固反应   Ag@Ag2S核壳  

摘要： 采用两步法了合成Ag@Ag2S核壳纳米颗粒。首先以无水乙醇为还原剂,PVP(K-30)为分散剂,AgNO3为原料,采用溶剂热法合成出银纳米颗粒,随后在真空管式炉中对银纳米粉体进行硫化。紫外可见吸收光谱(UV-vis),X射线衍射(XRD),透射电子显微镜(TEM)的结果表明,以450℃加热硫粉,银粉所处位置为80℃,硫化时间为20~80min,成功制备出了Ag@Ag2S核壳结构纳米颗粒,颗粒粒径约为100±30nm。

关键词： 自组装有机单分子   Ag纳米颗粒   化学镀法   微接触印刷  

摘要： 一步法完成Ag纳米颗粒的制备及图案化组装,开辟低成本、高效率制备图案化银纳米颗粒单层膜的新途径。采用微接触印刷技术,将有机分子十六烷基硫醇(HDT),1,10-癸二硫醇硫醇(DDT)选择性自组装在金表面,通过化学镀法在基底材料上制备高度分散有序直径约为10nm的球形银纳米颗粒。得到规则有序的图案化银纳米颗粒单层膜。采用自主装诱导技术结合化学镀法,制备Ag纳米颗粒的同时,完成图案化银纳米颗粒薄膜的制备。图案化分散有序的金属纳米颗粒在表面催化和微电子器件制备方面有广阔的应用前景。

关键词： Ag/Al2O3粉体   溶胶-凝胶法   反应合成法   分散度  

摘要： 研究了采用溶胶凝胶法和反应合成法制备的Ag/Al_2O_3粉体中纳米银的尺寸和分散度,并应用XRD、TEM、SEM技术对其进行表征。结果表明,反应合成法制备的粉体,Ag颗粒分布在氧化铝上面,尺寸大约为100nm,而溶胶凝胶法制备的粉体更为细小。溶胶凝胶法制备粉体中只存在Al2O3的结构,XRD表明并没有出现Ag或AgO的特征衍射峰,而且银高度分散在Al2O3的表面,没有进入Al_2O_3的晶体结构中。在氧气气氛下,反应合成法制备粉体时发生了固相变化,因此析出的Ag颗粒和基体的界面间存在键合的关系。

关键词： nanoparticles   oil-in-water self-assembly   Ag@AgCl/Bi2O2CO3   photocatalysis   methylene blue degradation   (BIO)(2)CO3 HIERARCHICAL MICROSPHERES   HIGHLY EFFICIENT   HYDROTHERMAL PREPARATION   FACILE SYNTHESIS   RHODAMINE-B   DEGRADATION   HETEROJUNCTION   PERFORMANCE   COMPOSITES   MICROSTRUCTURES  

摘要： In this work, a series of novel flower-like Ag@AgCl/Bi2O2CO3 were prepared by simple and feasible oil-in-water self-assembly processes. The phase structures of as-prepared samples were examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray fluorescence spectrometer (XRF), etc. The characterization results indicated that the presence of Ag@AgCl did not affect the crystal structure, but exerted a great influence on the photocatalytic activity of Bi2O2CO3 and enhanced the absorption band of pure Bi2O2CO3. The photocatalytic activities of the Ag@AgCl/Bi2O2CO3 samples were determined by photocatalytic degradation of methylene blue (MB) under visible light irradiation. The Ag@AgCl (10 wt %)/Bi2O2CO3 composite showed the highest photocatalytic activity, degrading 97.9% MB after irradiation for 20 min, which is over 1.64 and 3.66 times faster than that of pure Ag@AgCl (calculated based on the equivalent Ag@AgCl content in Ag@AgCl (10 wt %)/Bi2O2CO3) and pure Bi2O2CO3, respectively. Bisphenol A (BPA) was also degraded to further prove the degradation ability of Ag@AgCl/Bi2O2CO3. Photocurrent studies indicated that the recombination of photo-generated electron hole pairs was decreased effectively due to the formation of heterojunctions between flower-like Bi2O2CO3 and Ag@AgCl nanoparticles. Trapping experiments indicated that O-2(-), h(+) and Cl degrees acted as the main reactive species for MB degradation in the present photocatalytic system. Furthermore, the cycling experiments revealed the good stability of Ag@AgCl/Bi2O2CO3 composites. Based on the above, a photocatalytic mechanism for the degradation of organic compounds over Ag@AgCI/Bi2O2CO3 was proposed.

关键词： 二氧化硅膜   银纳米颗粒   形成机理   消光谱   陷光性能  

摘要： 采用磁控溅射法在Si衬底上制备了SiO_2介质膜,系统地研究了SiO_2膜引入对Ag纳米颗粒的表面覆盖率、形貌、形成机理和光学性质的影响.研究发现引入SiO_2介质膜后,Ag纳米颗粒的表面覆盖率显著增加,平均粒径明显降低.基于现有的Ag纳米颗粒形成机理,提出了粗糙表面Ag膜断裂模型以解释其形貌发生变化的原因.紫外-可见光分光光度计测试表明,引入SiO_2膜并优化其厚度,可使Ag纳米颗粒的偶极消光峰最大红移86nm,但消光峰强度明显下降.数值模拟计算表明,引入SiO_2膜的Ag纳米颗粒所能散射的光子数量最小减少2×10^(18)个.因此,在Si衬底上沉积SiO_2膜,不利于Ag纳米颗粒陷光性能的提高.

关键词： FILMS   COMPOSITES   RELAXATION   BEHAVIOR  

摘要： Polymeric nanocomposites were prepared by inserting graphene and/or Ag, Au and ZnO nanoparticles in a TEGDA (tetraethyleneglycol diacrylate) polymer matrix. The polymeric films were characterized in terms of their dielectric properties by electrochemical impedance spectroscopy. The impedance data were fitted by generalized relaxation functions in order to determine conductivity, dielectric response and molecular relaxation time of the nanocomposite films. In particular, a stretched exponential function, Kohlrausch-Williams-Watts function (KWW), was used to investigate polymer/graphene/metal nanocomposites. (c) 2016 Author(s).

关键词： Ag@PCz   nanocomposites   optical behavior   dispersion trend   COAXIAL NANOCABLES  

摘要： Ag nanoparticles (NPs) encapsulated by polycarbazole (PCz) have been synthesized using ion adsorption method. The PCz synthesis around Ag NPs has been performed by adsorbing Ag+1 and Fe+3 oxidants onto Ag NPs, which initiated surface polymerization and thus, Ag NPs@PCz nanocomposite has been synthesized. The morphology of pure NPs and composite NPs was characterized by TEM which also elucidated the effect of oxidant on the core NPs, beside their morphologies and phase contrasts of metal NPs and polymer. The polymer around the surface of core NPs was characterized by FT-IR which proved that PCz was the organic phase of the composite NPs. UV-Vis spectroscopy has been employed to study surface plasmon resonance (SPR) of pure NPs and composite of NP which demonstrated that SPR of core NPs remained preserved after coating with the polymer. Furthermore, Zeta Sizer Nano series has been applied to analyze the dispersion behavior of pure NPs and composite NPs which displayed the greatly improved dispersion behavior of the composite NPs as compared to pure Ag NPs. Therefore, our study proved helpful to analyze the suitability of metal oxidants for PCz based nanocomposite synthesis and determination of their optical and dispersion behavior.

关键词： Ag纳米颗粒   NaYF4∶Yb3+/Er3+   光致发光  

摘要： 利用水热法制备了Yb3+,Er3+共掺杂NaYF4上转换发光材料。在实验中引入Ag纳米溶胶,研究了Ag纳米颗粒对NaYF4∶Yb3+/Er3+上转换发光材料结构、形貌和光学性质的影响。通过X射线衍射(XRD)、扫描电子显微镜(SEM)以及荧光光谱仪对样品的结构、形貌和光学性能进行了研究。结果表明,生成NaYF4∶Yb3+/Er3+反应前加入Ag纳米颗粒可使NaYF4∶Yb3+/Er3+粉末的衍射峰强度增强;生成NaYF4∶Yb3+/Er3+反应后加入Ag纳米颗粒会使六方相样品部分转变成立方相。生成NaYF4∶Yb3+/Er3+发光材料前引入Ag纳米溶胶可以大大提升晶体的结晶质量;生成NaYF4∶Yb3+/Er3+发光材料后引入Ag纳米溶胶,原有六棱柱直径变小,产物有新的球状晶体生成。生成NaYF4∶Yb3+/Er3+反应前加入Ag纳米颗粒,可使NaYF4∶Yb3+/Er3+上转换材料的发光强度显著增强,与未掺杂Ag纳米颗粒相比发光强度增加约36%。

关键词： Sn3.5Ag0.5Cu纳米钎料   烧结   界面结构   剪切强度  

摘要： 采用液相法在室温下合成了直径为10 nm以下的Sn3.5Ag0.5Cu纳米颗粒,并采用SEM,TEM,XRD及EDS表征其形貌、结构、物相及元素组成特征,研究了不同温度和时间烧结时纳米颗粒的尺寸变化,测试了经过不同压力钎焊后的Cu/纳米钎料/Cu的三明治结构的剪切强度.结果表明:10 nm以下的纳米钎料颗粒呈现颈缩团聚的趋势;烧结温度越高,纳米颗粒的颈缩团聚越明显,整个过程发生越迅速;在230℃可以实现钎焊,低于传统微米尺度的Sn3.5Ag0.5Cu钎料的温度(250℃左右),且钎焊界面强度受钎焊压力影响较大,当压力为10 N时,三明治结构的剪切强度达到最大,为14.2 MPa.钎焊键合过程为首先通过纳米颗粒颈缩团聚减少气孔,随着温度的升高,熔化的钎料与固态母材之间的溶解扩散过程形成牢固的冶金连接.