云母模板中Cu纳米线的制备及其光学性质研究

Nanopores with diameters between 30 nm and 180 nm have been fabricated by inducing latent track with fast heavy ions and etching process in 25 μm thick,single-crystal muscovite mica.For short etching time,the nanopores are columns with circular cross section.For long etching time the cross section of nanopores becomes rhombic.Thus the shape of nanopores depends on the etching time.Cu nanowires have been fabricated with controlled dimensions by electrodeposition into the nanopores.The ultraviolet-visible lig...中文文摘：利用快重离子辐照的单晶白云母片产生潜径迹,蚀刻得到直径在30—180nm纳米孔道.孔道形状依赖于蚀刻时间,蚀刻时间短得到圆柱形孔道,蚀刻时间长得到菱柱形孔道.从而在云母模板孔道中电化学沉积得到不同直径和形状的Cu纳米线.通过紫外可见光谱分析,发现铜纳米线的尺寸和形状影响其光学性质.直径小于60nm的近似为圆柱状Cu纳米线有一个明显的表面等离子体共振峰和一个微弱的次峰.随着直径增加,菱柱状的Cu纳米线主峰有明显的红移,次峰逐渐增强.同时利用扫描电子显微镜、X射线衍射对Cu纳米线的形貌和晶体结构特征进行了表征.

Electrochemical fabrication of single-crystalline and polycrystalline Au nanowires: the influence of deposition parameters

We report the electrochemical growth of gold nanowires with controlled dimensions and crystallinity. By systematically varying the deposition conditions, both polycrystalline and single-crystalline wires with diameters between 20 and 100 nm are successfully synthesized in etched ion-track membranes. The nanowires are characterized using scanning electron microscopy, high resolution transmission electron microscopy, scanning tunnelling microscopy and x-ray diffraction. The influence of the deposition parameters, especially those of the electrolyte, on the nanowire structure is investigated. Gold sulfite electrolytes lead to polycrystalline structure at the temperatures and voltages employed. In contrast, gold cyanide solution favours the growth of single crystals at temperatures between 50 and 65 degrees C under both direct current and reverse pulse current deposition conditions. The single-crystalline wires possess a [110] preferred orientation.

Segmented All-Platinum Nanowires with Controlled Morphology through Manipulation of the Local Electrolyte Distribution in Fluidic Nanochannels during Electrodeposition

Synthesis of segmented all-Pt nanowires is achieved by a template-assisted method. The combination of a suitably chosen electrolyte/template system with pulse-reverse electrodeposition allows the formation of well-defined segments linked to nanowires. Manipulation of the morphology is obtained by controlling the electrokinetie effects on the local electrolyte distribution inside the nanochannels during the nanowire growth process, allowing a deviation from the continuously cylindrical geometry given by the nanoporous template. The length of the segments can be adjusted as a function of the cathodic pulse duration. Applying constant pulses leads to segments with homogeneous shape and dimensions along most of the total wire length. X-ray diffraction demonstrates that the preferred crystallite orientation of the polycrystalline wires varies with the average segment length. The results are explained considering transitions in texture formation with increasing thickness of the electrodeposit. A mechanism of segment formation is proposed based on structural characterizations. Nanowires with controlled segmented morphology are of great technological importance, because of the possibility to precisely control their substructure as a means of tuning their electrical, thermal, and optical properties. The concept we present in this work for electrodeposited platinum and track-etched polycarbonate membranes can be applied to other selected materials as well as templates and constitutes a general method to controlled nanostructuring and synthesis of shape controlled nanostructures.

重离子蚀刻径迹中金属纳米线阵列的研制

本论文主要进行了核孔膜的蚀刻和紫外光辐照效应研究，以及在核孔膜模板内进行Cu、CO金属纳米线阵列的制备研究。在UNILAC（GSI，Darmstadt）加速器上真空和室温条件下对30μm厚的聚碳酸酯（PC）薄膜进行快重离子辐照，照射离子为11． 4 MeV／u的Au离子，辐照剂量在lion／cm，-3X109i0ns／cm，之间。重离子辐照导致在PC中产生潜径迹，通过化学蚀刻的方法将潜径迹放大而形成孔道。蚀刻速率与蚀刻温度、蚀刻液浓度、紫外光辐照敏化等参数密切相关。结果表明随着温度的升高蚀刻液浓度的增加、紫外光辐照时间的增长径迹蚀刻速率剧烈增加。此外，通过紫外可见光谱和力学性能测试发现，紫外光辐照会使Pc膜的光学性能和力学性能发生显著的变化。在能量密度为16mw／cm2的紫外光下，当膜两侧分别经过17．5小时的光照以后，392 nm处的吸收峰消失，而且其断裂伸长率大大减小。作为紫外光辐照效应的一个应用，我们利用“紫外光辐照＋液氮冷冻”的方法成功制备出了核孔膜断面的扫描电子显微镜样品，此方法能使样品的断面含有较少的残余应力从而使膜在断裂过程中没有发生明显的变形，使断面很好显现了膜和孔道的原始信息，如孔密度、形状、尺寸等。利用PC核孔膜作为模板用电化学沉积方法制备出了金属纳米线阵列。用磁控溅射的方法在PC膜模板的一面沉积一层Pt金属薄膜在电沉积过程中用作阴极。在自制的电沉积系统中用直流沉积的方法在PC核孔膜模板中成功制备出了Cu和Co金属纳米线，并运用SEM、xRD、VSM等手段对纳米线进行分析。结果表明，制备出的Cu纳米线长度约为30μm，直径从nm到协m量级，具有面心立方（fcc）结构，且纯度很高没有发现杂质。对Co纳米线阵列的xRD结果进行分析可以看出，制备出的c。纳米线阵列具有两种晶体结构：单相hcp结构和hcp、fcc共存结构。从vsM测量结果可以看出，Co纳米线阵列存在磁各向异性，即平行于纳米线轴向和垂直于纳米线轴向的剩余磁化强度和矫顽力存在明显差异，这主要是由于纳米线的形状各向异性和纳米线之间的磁相互作用引起的。

A general method for the rapid synthesis of hollow metallic or bimetallic nanoelectrocatalysts with urchinlike morphology

We have reported a facile and general method for the rapid synthesis of hollow nanostructures with urchinlike morphology. In-situ produced Ag nanoparticles can be used as sacrificial templates to rapidly synthesize diverse hollow urchinlike metallic or bimetallic (such as Au/Pt) nanostructures. It has been found that heating the solution at 100 degrees C during the galvanic replacement is very necessary for obtaining urchinlike nanostructures. Through changing the molar ratios of Ag to Pt, the wall thickness of hollow nanospheres can be easily controlled; through changing the diameter of Ag nanoparticles, the size of cavity of hollow nanospheres can be facilely controlled; through changing the morphologies of Ag nanostructures from nanoparticle to nanowire, hollow Pt nanotubes can be easily designed. This one-pot approach can be extended to synthesize other hollow nanospheres such as Pd, Pd/Pt, Au/Pd, and Au/Pt. The features of this technique are that it is facile, quick, economical, and versatile.

Nanoporous In2O3 nanocrystal clusters: One-step synthesis, thermal stability and optical property

Nanoporous In2O3 nanocrystal clusters with high surface areas have been synthesized by a one-step solvent-thermal method at a relatively low temperature. On the basis of our experimental data and nanomaterial growth mechanism, a template-assistant dehydration accompanied by aggregation mechanism was proposed to explain their formation. Besides, the influence of the high-temperature treatment on their porous structure and optical properties were studied and compared by various technologies.

Template-free, surfactantless route to fabricate In(OH)(3) monocrystalline nanoarchitectures and their conversion to In2O3

In this work, a one-dimensional microrod-based three-dimensional flowerlike indium hydroxide (In(OH)(3)) structure was fabricated, without any templates or surfactants, using a well-known hydrothermal approach at a non-high temperature. In2O3 with similar morphology was formed by annealing In(OH)3 precursors and was characterized by Raman spectrum and photoluminescence (PL) spectrum in detail.

Self-assembled 3D microflowery In(OH)(3) architecture and its conversion to In2O3

Using sodium dodecyl sulfate (SDS), a 3D microflowery indium hydroxide [In(OH)(3)] structure assembled from 2D nanoflakes was fabricated in a large quantity via a hydrothermal approach at relative low temperature. The obtained In(OH)(3) flowers exhibited a narrow size range between 4 and 6 mu m. The properties of these composites were characterized by XRD, EDX, FE-SEM, TEM, SAED, and TGA. In this work, both the use of urea and SDS and the amounts of these components played important roles in the formation of In(OH)3 with different nanostructures.

Preparation of ferrite MFe2O4 (M = Co, Ni) ribbons with nanoporous structure and their magnetic properties

Spinel ferrite, MFe2O4 (M = Co, Ni), ribbons with nanoporous structure were prepared by electrospinning combined with sol-gel technology. The ribbons were formed through the agglomeration of magnetic nanoparticles with PVP as the structure directing template. The length of the polycrystalline ribbons can reach millimeters, and the width of the ribbons can be tuned from several micrometers to several hundred nanometers by changing the concentration of precursor. The nanoporous structure was formed during the decomposition of PVP and inorganic salts.

Biofilm-Engineered Nanostructures

The use of biofilms as nanostructure-engineering materials is discussed and exemplified using ZnO nanorods. Three examples are presented for illustration, the immobilization of ZnO-nanorod arrays on the inner wall of a polystyrene centrifuge tube using S. thermophilus, the morphological organization of ZnO "filters" using S. thermophilus. And the design and implementation of a ZnO-decorated Ag framework using E. coli.

CuIn(WO4)(2) nanospindles and nanorods: controlled synthesis and host for lanthanide near-infrared luminescence properties

CuIn(WO4)(2) porous nanospindles and nanorods were synthesized through a low-cost hydrothermal method without introducing any template or surfactants. An interesting formation mechanism, namely "oriented attachment", was observed for the growth of nanorods based on the experimental process and the anisotropic intrinsic crystalline structure of CuIn(WO4)(2), which is uncommon in such a system. The near-infrared luminescence of lanthanide ions (Er, Nd, Yb and Ho) doped CuIn(WO4)(2) nanostructures, especially in the 1300-1600 nm region, was discussed and of particular interest for telecommunications applications. X-Ray diffraction, scanning electron microscopy, transmission electron microscopy, electron diffraction and photoluminescence spectra were used to characterize these materials.

Preparation of Hollow Carbon and Silicon Carbide Fibers with Different Cross-Sections by using Electrospun Fibers as Templates

Hollow carbon nanofibers with circular and rectangular opening were prepared by using electrospun silica fibers as templates. Silica fibers were synthesized by electrospinning, and they were coated with a carbon layer formed by thermal decomposition and carbonization of polystyrene under a nitrogen atmosphere. Hollow carbon nanofibers with circular and rectangular openings were then obtained after the silica core was etched by hydrofluoric acid. The carbon nanofibers with different morphologies also could be used as templates to fabricate silicon carbide fibers. The silicon carbide fibers with circular and rectangular openings could be obtained by using hollow carbon nanofibers and carbon belts as templates, respectively.

Crystal Growth Transition from Flat-On to Edge-On Induced by Solvent Evaporation in Ultrathin Films of Polystyrene-b-Poly(ethylene oxide)

The transition of lamellar crystal orientation from flat-on to edge-on in ultrathin films of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) via solvent vapor (toluene) treatment Was investigated. When the as-prepared film was treated in saturated solvent vapor, breakout crystals could form quickly, and then they transformed from square single crystals (flat-on lamellae) to dendrites and finally to nanowire crystals (edge-on lamellae). Initially, heterogeneous nucleation tit the polymer/substrate interface dominated the structure evolution, leading to flat-on lamellar crystals orientation. And the transition from faceted habits to dendrites indicated a transition of underlying mechanism from nucleation-controlled to diffusion-limited growth. As the solvent molecules gradually diffused into the polymer/substrate interface, it will subsequently weaken the polymer-substrate interaction.