Porous anodic alumina (PAA) membranes with highly ordered hexagonal cells and a novel pore structure have been fabricated by two-step hard anodization in a H(2)SO(4)-Al(2)(SO(4))(3)-H(2)O system at 40 and 50 V, giving average cell diameters of 77 and 96 nm, respectively. There are several tiny pores embedded in each big shallow pore on the top of the membranes, and there is only one pore in one cell at their bottom. The cells on both sides of the membranes present almost the same periodic arrangement. In order to explore the formation of the novel pore structure, PAA membranes fabricated at different current densities (30-200 mA cm(-2)) are obtained by maintaining a constant voltage at 40 V. The experimental results show that the interpore distance is not only dependent on the anodization voltage, but is also influenced by the current density, which means that the pore structure of PAA membranes fabricated by hard anodization can be accurately designed and controlled by adjusting the anodization voltage and current density simultaneously.

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Mn 1.85 Co 0.3 Ni 0.85 O 4 thin films with single cubic spinel phase and compact surface were prepared by chemical solution deposition method on Al2O3 substrates. Temperature dependent ac impedance spectroscopy was employed to analyze the contributions of grain boundary (GB) and grain to the conduction mechanism. The major characteristics (hopping type, resistance versus temperature behavior, and characteristic temperature T0) of the GB and grain were obtained. The hopping type of GB is nearest-neighbor-hopping (NNH), and that of grain might be a transition from variable-range-hopping to NNH. The GB shows dominating resistance while the grain shows stronger temperature dependence.

Novel anodic aluminium oxide (AAO) films and hollow nanostructures were synthesized via a simple electrochemical and chemical etching route; fluctuating nanotube growth inside AAO film fabricated under ultra-high voltage was considered to be the main reason for the formation of such new structures.