A transparent porous alumina nanostructure was formed on a glass covered tin-doped indium oxide (ITO) substrate by anodization of a highly pure sputtered aluminum layer. Details of the fabrication and microstructures of porous anodic alumina films are described and a possible mechanism of anodization is outlined. The variation of anodic current density reflects three processes, i.e., (i) anodization of the sputtered aluminum layer, (ii) transition of electrolysis from aluminum to the underlying ITO film, and (iii) electrochemical reactions on the ITO film beneath the anodic alumina film. As all the aluminum is completely anodized, the resultant oxide films on the ITO/glass substrate possess a parallel porous structure (ϕ80-100 nm, cell size in ∼350 nm) with a thin arched barrier layer (∼80 nm) and exhibit a high transmittance in the ultraviolet-visible light range (75-100% transmittance 300-900 nm). © 2002 The Electrochemical Society. All rights reserved.

Titania nanostructures with larger surface areas are fabricated on a glass substrate by anodization of sputtered aluminum and the sol−gel process, and the structural characteristics of the nanostructures are investigated. Highly pure aluminum film (99.99%, ≈2 μm), which is deposited on a glass substrate with a conductive tin-doped indium oxide (ITO) layer, is first anodized potentiostaticly in a phosphoric acid solution to obtain porous alumina structures. The anodic alumina is then used as a host or template to synthesize porous Al2O3/TiO2 composite nanostructures through a sol−gel process. Finally, a TiO2 nanotubules array with contours of porous anodic alumina is fabricated on glass by removing the alumina template selectively. The resultant TiO2 is 4−20 nm polycrystalline of anatase structure with (101) preferential orientation. Titania nanostructures have large surface areas and exhibit a high transmittance in visible light and a strong absorbance within ultraviolet range in UV−vis spectra. Moreover, the fabrication of composite TiO2−xSiO2−xTeO2 (x = 2.5%, 5%) nanostructures is also investigated. Addition of appropriate SiO2 and TeO2 to TiO2 enhances not only the adhesion to the substrate but also the mechanical strength of the nanotubules, while showing little effect on the crystallinity and the UV−vis absorbance of TiO2.

A novel process for fabrication of metal nanostructure arrays directly on glass substrates is described. An aluminum film was sputter-deposited on a glass substrate coated with a tin-doped indium oxide (ITO) film. The films were then anodically oxidized to obtain a porous alumina template, with pore diameters ranging from 5 to 150 nm, which was used as a template-electrode in a direct current electrodeposition to fabricate various nickel nanowires (L 18-180 nm, 0.5-2.6 µm long) in the nanopores. The porous alumina films not only define the dimensions of the nanowires but also influence the crystalline orientation. The magnetic hysteresis measurement showed that the Ni nanowire arrays have significant magnetic anisotropy proportional to their aspect ratios. The coercivity (H c ) and the squareness (M r /M s ) perpendicular to the substrates were 1025 Oe and 0.74 for the Ni nanowires of L 50 nm (1.8 µm), and 830 Oe and 0.94 for the Ni nanowires of L 18 nm (1.2 µm), respectively.

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The Ωt intensity parameters (t=2,4,6) of Er3+ ions in several oxide glasses and the isomer shift (IS) of 151Eu Mössbauer spectra in glasses of the same composition were determined. Among these Ωt’s, the Ω6 parameter was found to have a good relation with IS; Ω6 decreases with an increase of IS which reflects the 6s electron density of rare-earth ions. From the theoretical expression of Ωt, Ω6 is considered to be more affected by the overlap integrals of the 4f and 5d orbitals than Ω2 and Ω4, and to increase with an increase of these overlap integrals. These overlap integrals are supposed to decrease when the 6s electron density is larger, since the 6s electron density shields the 5d electron orbital.