Synthesis of ordered Al nanowire arrays

Ordered Al nanowire arrays with the same nanowire density but the diameters decrease radially embedded in one piece of anodic alumina membranes were successfully fabricated by two-step synthesis: electrodeposition of Zn and replacement in AlCl₃ solution. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected-area electron diffraction techniques were used to characterize the Al nanowires obtained. SEM and TEM images taken from the different areas of Al nanowire arrays show that we can control the growth of aligned Al nanowires with different diameters in a single process at the same time. The investigation results not only have potential applications in photoelectric devices but also open up a new method for fabricating nano-scale materials.     

Electrodeposited highly-ordered manganese oxide nanowire arrays for supercapacitors

Large arrays of well-aligned Mn oxide nanowires were prepared by electrodeposition using anodic aluminum oxide templates. The sizes of nanowires were tuned by varying the electrotype solution involved and the MnO₂ nanowires with 10 μm in length were obtained in a neutral KMnO₄ bath for 1 h. MnO₂ nanowire arrays grown on conductor substance save the tedious electrode-making process, and electrochemical characterization demonstrates that the MnO₂ nanowire arrays electrode has good capacitive behavior. Due to the limited mass transportation in narrow spacing, the spacing effects between the neighbor nanowires have show great influence to the electrochemical performance.     

Fabrication of lead titanate single crystalline nanowires by hydrothermal method and their characterization

Single crystalline nanowires of lead titanate (PbTiO₃) were fabricated by hydrothermal method at 200°C using lead acetate and n-tetrabutyl titanate as starting materials, where sodium hydroxide was served as a mineralizer. Crystalline phases, microstructure and optical properties of PbTiO₃ nanowires were investigated. The PbTiO₃ nanowires were uniform and continuous along the long axis, and were composed of single crystalline PbTiO₃ with a tetragonal perovskite structure. The diameter of a single nanowire was around 12 nm and the length reached up to 3 μm. The chemical composition of the samples and the valence states of elements were determined by X-ray photoelectron spectroscopy (XPS). The ultraviolet/visible absorption spectroscopic investigation suggested that the absorption edge of optical transition of the first excitonic state occurred at around 320 nm. A blue-green light emission peaking at about 471 nm (2.63 eV) is observed at room temperature, and the intensity of this emission increased with increasing excitation wavelength. Oxygen vacancies are responsible for the light emission of PbTiO₃ nanowires.     

Epitaxial Growth and Thermoelectric Measurement of Bi2Te3/Sb Superlattice Nanowires

Superlattice nanowires are expected to show further enhanced thermoelectric performance compared with conventional nanowires or superlattice thin films. We report the epitaxial growth of high density Bi₂Te₃/Sb superlattice nanowire arrays with a very small bilayer thickness by pulse electrodeposition. Transmission electron microscopy, selected area electron diffraction and high resolution transmission electron microscopy were used to characterize the superlattice nanowires, and Harman technique was employed to measure the figure of merit (ZT) of the superlattice nanowire array in high vacuum condition. The superlattice nanowire arrays exhibit a ZT of 0.15 at 330 K, and a temperature difference of about 6.6 K can be realized across the nanowire arrays.     

Pulse deposition of large area,patterned manganese oxide nanowires in variable aspect ratios without templates

Manganese oxide nanowires with β-MnOOH in core and Mn₃O₄ in shell were successfully plated onto various conductive substrates from a Mn(CH₃COO)₂ solution by anodic deposition under a two-electrode, pulse-rest mode. The aspect ratio of uniform nanowire morphologies in cm² scale is controllable by varying the deposition variables. Patterned MnO_x nanowire arrays were obtained by combining lithographic and electroplating techniques demonstrated to be a powerful method for preparing MnO_x nanowires in the field emission (FE) array cathodes with a low turn-on voltage (∼3.4 V/μm at 1 μA/cm²).     

CdSe纳米线阵列的制备及其表征(英)

通过在含有SeSO₃^2-和Cd²⁺的室温水溶液中，用模板-电沉积法在纳米孔阵列阳极氧化铝膜(AAM)模板中制备了高有序性的CdSe纳米线阵列，并对其形貌、结构和组分进行了表征。扫描电子显微镜(SEM)和透射电子显微镜(TEM)结果表明，纳米线阵列中的CdSe纳米线具有相同的长度和直径，分别对应于使用的AAM模板的厚度和孔径；X-射线衍射(XRD)和X-射线能谱(EDAX)结果表明，CdSe纳米线中Cd和Se的化学组成非常接近于1∶1，其结构为立方CdSe。另外，对模板-电沉积法制备CdSe纳米线的机理进行了讨论。     

Highly ordered MnO2 nanowire array thin films on Ti/Si substrate as an electrode for electrochemical capacitor

AAO/Ti/Si substrate was successfully synthesized by a two-step electrochemical anodization of the aluminum film on the Ti/Si substrate and then used as template to grow nanowire arrays. The ordered MnO₂ nanowire arrays with about 40 nm diameters had been directly fabricated on AAO/Ti/Si substrate by direct current (DC) electrodeposition. The microstructure of the nanowire arrays was investigated by field-emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Their electrochemical characterization was performed using cyclic voltammetry in 0.5 M Na₂SO₄ aqueous solution. The synthesized MnO₂ nanowires had amorphous nature until 400 °C. The deal capacitive behavior was obtained when the as-prepared sample was heat-treated at 200 °C. The specific capacitance of the electrode was about 254 F/g.     

Ordered nickel oxide nanowire arrays and their optical absorption properties

Ordered NiO nanowire arrays embedded in anodic alumina membranes have been prepared by using an electrochemical deposition method. After annealing at 300 °C, the NiO nanowire arrays were characterized using SEM, TEM, SAED, and XRD. SEM and TEM observations reveal that these nanowires are dense, continuous and arranged roughly parallel to one another. XRD and SAED analysis together indicate that these NiO nanowires crystallize with a polycrystalline structure. The optical absorption band gap of NiO nanowire arrays is 3.74 eV, and no obvious blue shift or red shift with respect of that of the bulk NiO can be observed.     

MnS纳米线阵列上MnS花状球的水热合成

通过水热处理的方法,在氧化铝模板表面生成的MnS纳米线阵列上合成了六方相MnS花状球。利用场发射扫描电镜,透射电子显微镜,高分辨透射电子显微镜,选区电子衍射和X射线衍射对制备的样品进行了分析与表征。结果表明MnS花状球是在MnS纳米线阵列上生长的,纳米线的直径为70～80nm,与氧化铝模板的孔径一致且结晶性较好。随着阳极氧化氧化铝模板(AAO)的孔洞长度的减少,MnS花状球的数量快速增加。提出了MnS复合纳米结构可能的生长机制:氧化铝模板和反应中硫脲分解产生的H2S气体对产物的最终形貌有很重要的影响。室温光致发光光谱显示在420nm处存在一个很强的MnS带边发射峰。     

不同取向的CoSb3纳米线阵列的电化学法制备

近年来,金属纳米线及其阵列由于其新奇的物理和化学特性和在纳米器件方面潜在的应用前景,越来越受到人们的关注。氧化铝模板合成一维纳米材料具有设备简单、制作方便等优点,因而成为近年来人们常用的一种方法。利用电化学沉积的方法在多孔氧化铝模板中沉积各种成分的纳米线已成为纳米材料制备的一种常见的方法。这种方法不仅可以得到大面积有序的纳米线阵列,还可以根据需要调节孔洞的大小来控制纳米线的直径[1￣3]。最近理论研究结果预言[4￣6],由于纳米材料的量子限域效应,热电材料的纳米线将有比其相应块体材料更高的品质因数n,这极大地激…     

一种新的电化学方法制备CdS纳米线阵列

用一种新的电化学方法在多孔氧化铝模板中制备了CdS纳米线阵列体系,并用XRD、TEM对样品进行表征,结果显示CdS纳米线为立方相和六方相的多晶混合结构,对沉积机理进行了讨论.荧光光谱测量显示CdS纳米线阵列体系有三个强的紫外发光带和一个黄绿发光带.该文所使用的方法可以用来在氧化铝模板中制备其它材料的纳米线阵列体系.     

模板组装Fe纳米线阵列及其微结构

铝在硫酸溶液中经直流阳极氧化,得到多孔铝阳极氧化膜(AAO). 以AAO膜为模板,通过交流电沉积的方法,在AAO模板孔内成功组装了Fe纳米线.TEM分析表明,Fe纳米线的长度约为2.5 μm,其长度分布十分均匀；粗细均匀,直径约为25 nm. XRD实验分析证实,所制备的Fe纳米线为α-Fe.选区电子衍射（SAED）实验分析表明,α-Fe纳米线具有单晶结构.     

Boron-assisted growth of silica nanowire arrays and silica microflowers for bendable capacitor application

Aligned-long silica nanowire arrays and microflowers were synthesized with boron as catalyst. Besides that parallel plate capacitors were fabricated using the silica nanowire mat as a dielectric. Their frequency response and mechanical properties were investigated.     

Ambient template synthesis of multiferroic MnWO4 nanowires and nanowire arrays

The current report describes the systematic synthesis of polycrystalline, multiferroic MnWO₄ nanowires and nanowire arrays with controllable chemical composition and morphology, using a modified template-directed methodology under ambient room-temperature conditions. We were able to synthesize nanowires measuring 55±10, 100±20, and 260±40 nm in diameter, respectively, with lengths ranging in the microns. Extensive characterization of as-prepared samples has been performed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and energy-dispersive X-ray spectroscopy. Magnetic behavior in these systems was also probed.     

Electrochemical synthesis of ordered alumina nanowire arrays

Ordered Al₂O₃ nanowire arrays embedded in the nanochannels of anodic alumina membranes (AAMs) were synthesized by electrodepostion at room temperature. Our synthetic route yielded large quantities of Al₂O₃ nanowires of uniform size and shape that are ~40 μm long with diameters of 70 nm. The Al₂O₃ nanowire structures were characterized by scanning and transmission electron microscopies, high-resolution transmission electron microscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Electronic Publication     

Sol-Gel Template Synthesis of Highly Ordered LiCo0.5Mn0.5O2 Nanowire Arrays and Their Structural Properties

Highly ordered LiCo_0.5Mn_0.5O₂ nanowire arrays were prepared using porous anodic aluminum oxide (AAO) template from sol-gel solution containing Li(CH₃COO), Co(CH₃COO)₂, and Mn(CH₃COO)₂. Electron microscope results showed that uniform length and diameter of LiCo_0.5Mn_0.5O₂ nanowires were obtained, and the length and diameter of LiCo_0.5Mn_0.5O₂ nanowires are dependent on the pore diameter and the thickness of the applied AAO template. X-ray diffraction and electron diffraction pattern investigations demonstrate that LiCo_0.5Mn_0.5O₂ nanowires are a layered structure of LiCo_0.5Mn_0.5O₂ crystal. X-ray photoelectron spectroscopy analysis indicates that the most closely resembling stoichiometric layered LiCo_0.5Mn_0.5O₂ material has been obtained.     

Large‐Scale Synthesis of Necklace‐Like Single‐Crystalline PbTiO3 Nanowires

Summary: We show in this communication that large‐scale necklace‐like single‐crystalline tetragonal perovskite PbTiO₃ nanowires can be obtained via a simple electrospinning method. The morphology and the crystal structure are investigated by SEM, XRD, and HRTEM. The length of the necklace‐like PbTiO₃ nanowires is from tens to several tens of micrometers, the wider the diameter of it is between 100 and 200 nm and the thinner the part is between 20 and 50 nm. The necklace‐like PbTiO₃ nanowires exhibit high surface photovoltage under the action of external electric field, which is probably applicable in displaying photoelectric devices of heterojunction structure.

SEM image of the electrospinning necklace‐like PbTiO₃ nanowires.     

Hierarchical Titanate Nanostructures through Hydrothermal Treatment of Commercial Titania Powders

Hierarchical titanate nanostructures were hydrothermally synthesized in concentrated base solutions using commercial titania powders as starting materials. By varying the base concentration, nanowire arrays, flowers of nanosheets and nanotubes, and urchin‐like nanostructures of nanowires and nanotubes were sequentially fabricated. If the NaOH concentration was higher than 6 M , hydrated Na₂Ti₆O₁₃ nanowire arrays, with nanowire diameters of 20–90 nm and an aspect ratio of 1100–5000, were produced at suitable reaction temperatures over a large area. In 10 M KOH solutions, aligned nanowires with a diameter of 30 nm and a lenght of 80 μm formed. In 4 M NaOH solutions, micrometer‐sized flowers of nanotubes and nanosheets formed. Reactions in 2 M NaOH solutions produced urchin‐like materials with a size of ca. 10 μm that were composed of nanotubes and nanowires. The adsorption behavior of the urchin‐like materials resembled macroporous materials with micropores. Since both base concentration and reaction temperature affected the reaction rate, the formation of various titanate nanostructures was proposed as a growth speed controlled process.     

在样模制备法中影响有序金属Ni纳米线尺寸的因素

以多孔氧化铝为样模,运用电沉积法向样模的微孔中沉积金属Ni,制备得到了有序排列的金属Ni纳米线阵列;以透射电镜为主要表征手段,系统地研究了多孔氧化铝样模的制备条件对金属Ni纳米线尺寸的影响;结果表明：制备多孔氧化铝样模过程中的氧化介质、氧化温度、氧化电压以及氧化后的扩孔时间影响Ni纳米线的直径和长度,而电沉金属镍时的沉积电压和沉积时间则主要影响纳米线的长度。     

大面积Bi单晶纳米线阵列的制备

在有序的氧化铝模板(AAO)的孔洞中, 采用电化学沉积工艺成功地制备了准金属Bi纳米线有序阵列. 使用X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)及高分辨电子显微镜(HRTEM)对样品的结构和形貌进行了表征. XRD结果表明, 所制备的铋样品为六方相, 且沿[110]方向有很好的生长取向; FE-SEM图片清晰地说明铋纳米线阵列是大面积、填充率高和高度有序的; TEM的结果显示纳米线直径均匀、表面光滑且长径比大; HRTEM图片中清晰的晶格条纹和选区电子衍射(SAED)结果表明纳米线是单晶.