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Nanochannel arrays with the same nanochannel density but different nanochannel diameters in different areas in one piece of anodic alumina membrane had been created. SEM observations on one piece of this type of anodic alumina membrane show that the nanochannel diameters radially decrease from 80 nm to 60 nm and to 40 nm along the radial direction. Therefore, using this type of membrane as a template, ordered Ag nanowire arrays with the same nanowire density but with diameters decreasing radially were obtained by electrodeposition. SEM and TEM images taken of different areas of the Ag nanowire arrays show that we can control the growth of aligned Ag nanowires with different diameters in a single process at the same time. Using this type of template in combination with other fabrication techniques, nanometer-scale fibrils, rods, wires, and tubules of metal, semiconductors, carbon, and other materials with same density but different diameters in different areas can be fabricated. The simultaneous integration of ordered nanowire structures with different diameters embedded in a single anodic alumina membrane could be useful in nanodevice manufacture as well as electronics, optoelectronics and magnetics. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Co&z.sbnd;Fe&z.sbnd;P alloy nanowire arrays have been fabricated by autocatalyzed electroless deposition in an anodic alumina membrane (AAM). The images of Co&z.sbnd;Fe&z.sbnd;P nanowire arrays and single nanowires are obtained by scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. Selected area electron diffraction (SAED), X-ray diffraction (XRD) and energy dispersive spectra (EDS) are employed to study the morphology and chemical composition of the nanowires. The results indicate that Co&z.sbnd;Fe&z.sbnd;P nanowire arrays are amorphous in structure. The magnetic property of alloy nanowire arrays is characterized by using a vibrating sample magnetometer (VSM). The hysteresis loops show that the easily magnetized direction of Co&z.sbnd;Fe&z.sbnd;P is parallel to the nanowire arrays and that the Co&z.sbnd;Fe&z.sbnd;P nanowire arrays have obvious magnetic anisotropy as a result of the shape anisotropy. Compared with the electrodeposition method, autocatalyzed electroless deposition needs neither a supply of power nor a sprinkling of gold on one side of the AAM before the deposition and some defects of electrodeposition can be overcome. [Copyright &y& Elsevier]

Large-scale CeO2 nanowires were prepared successfully by an improved sol–gel process within the nanochannels of porous anodic alumina templates. In this process, cerium nitrate and urea were used as precursors, cerium nitrate acted as cerium ions source, and urea offered a basic medium through its hydrolysis. The as-synthesized CeO2 nanowires can be indexed as a fluorite-structure and the size of nanowires is uniform, with diameters of about 70 nm. The formation mechanism of nanowires is also discussed here. This method is more efficient than a traditional sol–gel template process for small pore diameter templates. [Copyright &y& Elsevier]

We have successfully fabricated ordered crystalline Ag2S nanowire arrays by direct current electrodeposition into the nanochannels of porous anodic aluminum oxide templates from a dimethylsulfoxide solution containing AgNO3 and elemental S. X-ray diffraction and the selected area electron diffraction investigations demonstrate that the Ag2S nanowires are a uniform actanthite structure. Electromicroscopy results show that the nanowires are quite ordered with diameters of about 40 nm and lengths up to 5 μm. X-ray energy dispersion analysis indicates that the atomic composition of Ag and S is very close to a 2:1 stoichiometry. Furthermore, a possible mechanism for the formation of the Ag2S nanowires is proposed. [Copyright &y& Elsevier]