Narrow Results

FeNi nanowire arrays were fabricated into the pores of porous alumina template by a simple alternating current electrodeposition method in this work. FeNi nanowires with different diameters were obtained depending on the pore size arrangement of alumina templates. FeNi nanowire arrays exhibited obviously magnetic anisotropy, and the easy axis was along the nanowires. When the applied magnetic field was parallel to the nanowires, the coercivity (H_c) and the maximum remnant ratio (M_r/M_s) are considerable higher than those while the magnetic field perpendicular to the nanowires. FeNi nanowires prepared in this work are expected to be utilized as the perpendicular magnetic recording media. The magnetic domain structure and the magnetizing mechanism of FeNi nanowires were also been discussed.

Uniform and aligned ZnO nanotube arrays have been synthesized by annealing Zn nanowire arrays in anodic aluminum oxide (AAO) membrane. In our method, Zn nanowire arrays were fabricated by electrochemical deposition technique based on ordered nanoporous AAO, and then a heat-treatment method was used to convert Zn nanowire arrays to ZnO nanotube arrays. The ZnO arrays were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and absorption spectra. The results show that the polycrystalline ZnO nanotubes have a diameter of about 45 nm. This method can also be used to fabricate other metal oxide nanotube arrays.

Ferromagnetic (Ni, Co, Fe) nanowires were electrodeposited using AAO template. XRD analysis indicated that the ferromagnetic wires had preferred orientation. For longer deposition time, the nanowires with textured structure changed to single crystal. The investigation on the growth mechanism showed that in the initial stage, the nanowires were polycrystalline. Our TEM analysis revealed the transition from polycrystalline structure to single crystal from the bottom to the top. The growth mechanisms are probably due to the competition growth of the adjacent grains and the confinement of growth in the nano-sized hole of the AAO template.

Aligned silicon dioxide (SiO₂) submicro-wires have been synthesized from tetraethyl orthosilicate (TEOS) by anodic aluminum oxide (AAO) template method. The products were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS) and X-ray diffraction (XRD).

Silver nanoparticles (NPs) films with different nominal thicknesses were deposited on the anodic aluminum oxide (AAO) templates with pore diameter about 200 nm by thermal evaporation. These NPs films were used as the surface enhanced Raman scattering (SERS) active substrates. The microstructure and surface morphology of the films were studied by X-ray diffraction and scanning electron microscopy, respectively. The SERS activity of the films was investigated by Raman scattering of adsorbed rhodamine 6G (R6G) at different concentrations. The results revealed that the average diameter of Ag NPs in different samples is 58 nm, 75 nm, 93 nm and 108 nm, respectively. Ag NPs film on AAO template is very suitable as a SERS active substrate and can detect R6G molecules with a concentration of 10^-8 M. The intensity of the SERS spectra is related to both the Ag NPs size and interparticle distance. The sample with an average particle diameter of 93 nm has the highest SERS enhancement factor (1.3 × 10⁶).

Amorphous Ce${}_x$Fe${}_y$O${}_n$ nanowire arrays with diameters about 100 nm were fabricated in porous anodic aluminum oxide (AAO) template channels by chemical co-precipitation assisted by suction filtration. Ce${}_x$Fe${}_y$O${}_n$ nanowire arrays have distinct magnetic anisotropy behavior, and the axis parallel to the nanowire is magnetically “easy.” The magnetic properties of Ce${}_x$Mn${}_z$O${}_n$ and Ce${}_x$Fe${}_y$Mn${}_z$O${}_n$ nanowire arrays were investigated to compare with Ce${}_x$Fe${}_y$O${}_n$ nanowire arrays. The fluorescence spectra of Ce${}_x$Fe${}_y$O${}_n$ nanowires arrays mixed with Eu, Tb, Sm showed that their emission intensity displays regular change with the increase of the mole fraction of mixture. The emission intensity reached maximum with increasing of Eu or Sm-mixing from 2 mol% to 10 mol% at 591 nm, 709 nm or 607 nm, then decreased gradually. However, there is no obvious influence to fluorescence of Tb mixed Ce${}_x$Fe${}_y$O${}_n$ nanowire arrays, only one visible weak emission peak is present at 486 nm.