Ni-纳米TiO2微粒复合电沉积研究

在Watts型镀镍液中，分别加入粒径为80—100nm的TiO2的两种同质异构体：金红石型和锐钛型，得到了Ni-纳米TiO2微粒的复合沉积层．研究了电沉积工艺体系的pH值、电流密度、搅拌速度、镀液中TiO2的含量及添加剂对复合沉积层的表观和沉积层中TiO2含量的影响，确定了最佳工艺条件．通过能量色散谱和SEM，对复合沉积层成分及形貌分析，在最佳组成及工艺条件下，得到了复合微粒重量为5％-10％，且表观形貌良好的Ni—TiO2复合沉积层。     

Preparation and Surface Modification of Novel Vesicular Nano-Particle “Cerasome” with Liposomal Bilayer and Silicate Surface

A novel class of nano-hybrid materials, Cerasome, bearing a liposomal bilayer structure and a ceramic surface, has been developed by a sol-gel reaction of a double-chain proamphiphile having an trialkoxysilane in the head moiety and followed self-assembling. In the present work, we developed new methods for preparation of the Cerasomes forming under various pH conditions and their surface modification by employing appropriate alkoxysilane compounds. When the proamphiphilic alkoxysilane was hydrolyzed in an acidic ethanol and then injected into an aqueous media at various pH, the morphologically stable Cerasomes were obtained in a wide pH range. On the other hand, an acid treatment of the proamphiphile in ethanol in the presence of tetraethoxysilane gave the Cerasome with highly developed siloxane networks on its vesicular surface. Surface modification of the Cerasome with amino groups was readily achieved in the similar manner by replacing tetraethoxysilane to 3-aminopropyltriethoxysilane. The Cerasomes thus prepared were characterized by means of dynamic light scattering and zeta potential measurements.     

喷墨打印制备LiMn2O4薄膜电极及其电化学性能

通过溶胶-凝胶法制备了尖晶石LiMn2O4. 用分散剂Lormar D, 经超声分散制得了含LiMn2O4粒子的打印“墨水”, 并使用计算机喷墨打印的方法制得LiMn2O4薄膜电极. 薄膜电极的厚度约为1.8 μm. 用XRD、TG-DTA、SEM、循环伏安、电化学阻抗谱和充放电等方法对材料和电极的性能进行了表征. 结果表明, 在较大电流100 μA·cm-2 (2C)的充放电情况下, 电极能保持好的稳定性,其首次放电容量为109 mAh·g-1, 充放电54次后, 其容量仍可保持97.4%, 为105 mAh·g-1, 这可归因于薄膜电极中尖晶石LiMn2O4的晶型完整, LiMn2O4粒子小以及稳定的超薄电极结构.     

Anti-Reflective Coatings for CRTs by Sol-Gel Process

Anti-reflective and electromagnetic shielding double-layered coatings were developed for cathode ray tubes (CRTs) by wet chemical process. An outer SiO₂ layer is formed over a porous inner tin-doped indium oxide (ITO) particle layer. ITO particles used in the inner layer lower the sheet resistance below 10³ohm/sq. and an electromagnetic shielding property is attained. To improve the abrasion wear resistance of the film, the structure of the film and hydrolysis-polymerization condition of tetraethoxy-silane (TEOS) are estimated. An outer SiO₂ layer component penetrates into the inner layer and adheres to the glass surface. As the extent of hydrolysis of TEOS proceeds and the molecular weight of hydrolyzed TEOS becomes small, the abrasion wear resistance of the film enhances. The relation between the curing condition of the film and surface resistance of the film is investigated. The surface resistance of the film lowers by curing the film in reductive atmosphere. The transmittance of the film in the near-infrared region shows that the lowering of surface resistance of the film is caused by the increase of carrier concentration of ITO particles. The double layered coatings are successfully applied to the panel glass for CRTs on an industrial-scale.     

金属颗粒对微小孔激光器增强透射的研究

制备了带有金属纳米颗粒结构的微小孔径垂直腔面发射激光器(NA-VCSEL)。当小孔和金属颗粒的直径分别为400 nm和100 nm时,其最大输出光功率达到了0.5 mW,比400 nm单个小孔的最大输出光功率提高了0.2 mW。实验和理论验证了金属纳米颗粒结构对NA-VCSEL输出光功率的增强作用。     

Effect of nano-particle size on product distribution and kinetic parameters of Fe/Cu/La catalyst in Fischer-Tropsch synthesis

Effects of nano-particle size on hydrocarbon production rates and distributions for precipitated Fe/Cu/La catalysts in Fischer-Tropsch synthesis were investigated. Nano-structured iron catalyst was prepared by micro-emulsion method. The concept of two superimposed Anderson-Schulz-Flory (ASF) distributions has been applied for the representation of the effects of reaction conditions and nano-particles size on kinetics parameters and product distributions. These results reveal that by reducing the particle size of catalyst, the break in ASF distributions was decreased. Also useful different kinetics equations for synthesis of C_3 to C_9 and C_(10) to C_(22) were determined by using α_1 and α_2 chain growth probabilities.     

Superparamagnetism and spin-glass like state for the MnFe2O4 nano-particles synthesized by the thermal decomposition method

MnFe₂O₄ nano-particles with an average size of about 7 nm were synthesized by the thermal decomposition method. Based on the magnetic hysteresis loops measured at different temperatures the temperature-dependent saturation magnetization (M_S) and coercivity (H_C) are determined. It is shown that above 20 K the temperature-dependence of the M_S and H_C indicates the magnetic behaviors in the single-domain nano-particles, while below 20 K, the change of the M_S and H_C indicates the freezing of the spin-glass like state on the surfaces. By measuring the magnetization–temperature (M–T) curves under the zero-field-cooling (ZFC) and field-cooling procedures at different applied fields, superparamagnetism behavior is also studied. Even though in the ZFC M–T curves peaks can be observed below 160 K, superparamagnetism does not appear until the temperature goes above 300 K, which is related with the strong inter-particle interaction.     

微观作用力驱动的纳米颗粒自装配技术

自装配技术在物理、生物化学、MEMS以及纳米制造等领域得到了广泛应用,对该领域的研究显示出重要的应用前景和重大的理论价值,成为一个充满生机活力的热点。本文在阐述微器件自装配领域研究成果的基础上,重点介绍了应用毛细力、亲水(疏水)力作为驱动力实现微器件的二维和三维功能结构自装配过程,并指出了目前研究方法在纳米级微器件三维功能结构自装配中存在的问题,最后提出了综合应用介电泳力、毛细力及亲水(疏水)力实现纳米颗粒与三维基体自装配的方法。     

磁性纳米材料固相萃取/火焰原子吸收光谱法测定环境水样中的痕量银离子

在纳米四氧化三铁表面包覆二氧化硅,并以十八烷基三甲氧基硅烷进行化学修饰,用作固相萃取吸附剂富集环境水样中的痕量银离子,用火焰原子吸收光谱法测定,建立了一种灵敏、快速、简便分析银离子的新方法。考察了水样pH值、吸附剂用量、螯合剂用量、振荡时间、洗脱剂、共存离子等对银离子回收率的影响。实验结果表明,对于200 mL水样,在pH 7.0、吸附剂用量为0.1 g、螯合剂5-Br-PADAP(0.5 g/L)用量为0.6 mL、吸附时间为10 min的条件下,材料对Ag+具有较好的吸附性,且用6 mL 1.0 mol/L的硝酸可完全洗脱所吸附的Ag+。在优化实验条件下,检出限(3σ)为0.15μg/L,相对标准偏差(10μg/L,n=6)为1.4%,富集因子达31。分别对河水、湖水样品中Ag+进行检测,加标回收率为85.0%~94.8%。     

斯托纳粒子的磁矩翻转

文章根据朗道-利夫席茨-吉尔伯特（Landau-Lifshitz-Gilbert）理论,介绍了斯托纳（Stoner）粒子（单个磁畴的磁性颗粒）磁矩翻转的相关理论.其中指出了有关磁矩翻转的斯托纳-沃尔法特（Wohlfarth）极限（SW极限）只有在阻尼系数无穷大时才是真正准确的.在此极限下,磁矩是沿着能量下降最快的路径翻转.最小的翻转磁场出现在当系统能量曲面中只有一个稳定的不动点的情形.文中还指出了对于一个给定的各向异性的磁体,阻尼系数存在一个临界值,超过它时,最小翻转磁场与SW极限是相同的.低于此临界值,最小翻转磁场可以小于SW极限.对于在有阻尼情况下的弹道式磁矩翻转,文中指出,施加的磁场方向应该处在一特定的方向内.这个方向窗口的宽度与阻尼系数和磁内能有关.对于一给定的磁内能,窗口的上下边界随着阻尼系数的增加而增加,窗口的宽度则随着阻尼系数的增加而呈振荡的变化.在没有阻尼和阻尼无穷大的极限下,窗口宽度变为零。