Synthesis of highly ordered LiMnO<Subscript>2</Subscript> nanowire arrays (by AAO template) and their structural properties

LiMnO₂ nanowire arrays were prepared using a porous anodic aluminum oxide (AAO) template from a sol–gel solution containing Li(OAc) and Mn(OAc)₂. Electron-microscope results showed that a uniform length and diameter of LiMnO₂ nanowires were obtained, and the length and diameter of the LiMnO₂ 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 LiMnO₂ nanowires are a layered structure of LiMnO₂ crystal. X-ray photoelectron spectroscopy analysis indicates that a material closely resembling stoichiometric layered LiMnO₂ has been obtained. Received: 2 September 2001 / Accepted: 6 January 2002 / Published online: 10 September 2002 RID="*" ID="*"Corresponding author. Fax: +86-931/891-2582, E-mail: lihl@lzu.edu.cn     

The fabrication of Ag nanoflake arrays via self-assembly on the surface of an anodic aluminum oxide template

Vertical-aligned Ag nanoflake arrays are fabricated on the surface of an anodic aluminum oxide (AAO) template under a hydrothermal condition for the first time. The porous surface of AAO templates and the precursor solution may play key roles in the process of fabricating Ag nanoflakes. The rim of pores can provide many active sites for nucleation and growth, and then nanoflake arrays gradually form through self-assembly of Ag on the surface of AAO membranes. The product is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and a growth mechanism of nanoflake is deduced. This work demonstrates that it is possible to make ordered nanoarrays without dissolving templates using the hydrothermal method, and this interesting Ag nanoflake arrays may provide a wider range of nanoscale applications.     

Alumina template-assisted electrodeposition of Bi2Te2.7Se0.3 nanowire arrays

Bi₂Te_2.7Se_0.3 nanowire arrays have been fabricated by electrodeposition into the pores of an anodic aluminum oxide (AAO) template followed by annealing at 300 °C under Ar atmosphere. The as-prepared nanowires were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. The nanowires are uniform single crystalline with diameter of ∼14 nm.     

Copper nanowire arrays for infrared polarizer

A micropolarizer of copper nanowire arrays within anodic alumina membrane (AAM) was fabricated by anodization of pure Al foil and electrodeposition of Cu, respectively. X-ray diffraction, scanning electron microscopy and transmission electron microscopy investigations reveal that the ordered Cu nanowires are essentially single crystal, and have an average diameter of 90 nm. Spectrophotometer measurements show that the copper nanowire arrays embedded in AAM can only transmit polarized light vertical to the wires. An extinction ratio of 24 to 32 dB and an average insertion loss of 0.5 dB in the wavelength range of 1 to 2.2 μm were obtained, respectively. Therefore Cu nanowire/AAM can be used as a wire grid type micropolarizer. Received: 28 January 2002 / Accepted:17 May 2002 / Published online: 22 November 2002 RID="*" ID="*"Corresponding author. Fax: +86-551/559-1434, E-mail: ytpang@263.net     

Highly ordered zinc oxide nanotubules synthesized within the anodic aluminum oxide template

Zinc oxide (ZnO) nanotubules were prepared by sol-gel synthesis within the pores of an anodic aluminum oxide (AAO) template. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and X-ray Diffraction (XRD) were used to investigate the morphology and crystalloid structures of the ZnO nanotubules. The results indicate that polycrystalline ZnO nanotubules are very uniformly assembled and parallel to each other in the membrane pores of the AAO template. Received: 15 January 2001 / Accepted: 1 February 2001 / Published online: 27 June 2001     

AFM study of gold nanowire array electrodeposited within anodic aluminum oxide template

Uniform gold nanowires were synthesized by electrodepositing the gold under a very low ac frequency in the pores of an anodic aluminum oxide (AAO) template. The surface of the Au/AAO composite is very even and appeared purplish red. Atomic force microscopy observation indicates that the template membranes we obtained have hexagonally close-packed nanochannels. The gold nanowire array is very orderly arranged after partially dissolving the aluminum oxide membrane. Gold nanowires were also characterized by transmission electron microscopy and the phase structure of the Au/AAO composite was proved by X-ray diffraction. Received: 19 April 2001 / Accepted: 28 April 2001 / Published online: 27 June 2001     

Formation of metal membranes by direct duplication of etched ion-track templates

A method for direct electrochemical metal duplication of pores in ion-track polymer membranes is described. It allows fabrication of metallic membranes using any metal, which is readily deposited by electroplating from aqueous solutions. The metal is deposited on one side of the template membrane, facing the anode, which is made conductive by a thin metal cladding layer. During electroplating, the lateral tapping of the pores is prevented by applying a counter-solution from the opposite non-metallized side of the plastic membrane, which increases dramatically the deposition overvoltage in the vicinity of the pore orifices. Such metallic membranes can be generated with pore diameters in the nano- and micrometer range and with densities from single pores up to 10⁶–10⁷ pores/cm². They can replace plastic filters in cases when an application of polymer material is not desirable. They could be advantageous particularly in catalysis as well as in biological science and technology. Further, they may be useful as apertures and collimators for different kinds of radiation. Received: 14 February 2002 / Accepted: 21 May 2002 / Published online: 22 November 2002 RID="*" ID="*"Corresponding author. Fax: +49-6159/712-179, E-mail: r.neumann@gsi.de     

Electrodeposition and magnetic properties of Ni nanowire arrays on anodic aluminum oxide/Ti/Si substrate

Ni nanowire arrays with different diameters have now been extended to directly fabricate in porous anodic alumina oxide (AAO) templates on Ti/Si substrate by direct current (DC) electrodeposition. An aluminum film is firstly sputter-deposited on a silicon substrate coated with a 300 nm Ti film. AAO/Ti/Si substrate is synthesized by a two-step electrochemical anodization of the aluminum film on the Ti/Si substrate and then used as template to grow Ni nanowire arrays with different diameters. The coercivity and the squareness in parallel direction of Ni nanowires with about 10 nm diameters are 664 Oe and 0.90, respectively. The Ni nanowire arrays fabricated on AAO/Ti/Si substrates should lead to practical applications in ultrahigh-density magnetic storage devices because of the excellent properties.     

Electrochemical synthesis of ordered CdTe nanowire arrays

Semiconductor CdTe nanowire arrays embedded in the nanochannels of the porous anodic alumina (PAA) template have been prepared by using a potentiostatic electrochemical deposition method. The morphology and structure of the CdTe nanowire arrays have been characterized by X-ray powder diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. It is found that the CdTe nanowires with diameters and lengths of about 60 nm are single-crystalline with cubic phase structure, uniformly and continuously embedded in the nanochannels of the PAA template. X-ray energy-dispersion analysis and X-ray photoelectron spectroscopy analysis indicate that stoichiometric CdTe was formed. The growth mechanism of the CdTe nanowires is also discussed. Received: 11 June 2002 / Accepted: 2 July 2002 / Published online: 8 January 2003 RID="*" ID="*"Corresponding author. Fax: +86-551/559-1434, E-mail: aiwuzhao@yahoo.com.cn     

模板法合成金属-分子-金属异质结及表面增强拉曼光谱研究

采用交流电沉积技术在阳极氧化铝(AAO)模板中沉积不同的金属纳米线,以对巯基苯(1,4-BDT)为耦联分子,通过自组装在模板内组装金属纳米粒子,由此构建金属纳米线-分子-金属纳米粒子的异质结.以异质结内的分子为探针,采用表面增强拉曼光谱(SERS)研究了异质结的增强行为,通过探针分子的SERS信号表达异质结的组成,并以异质结作为模型研究其SERS机理.研究结果表明该方法可成功构建异质结,同一取向的异质结的SERS信号较随机取向的SERS信号强.