Microstructure of nanopores in AAO templates favoring the growth of nickel nanowires by electrodeposition

Morphology of periodical nanoscale pores in AAO templates has been studied in relation with anodizing process, focusing on the growth of nickel nanowires by electrochemical deposition. The AAO templates were prepared by a two-step anodization process. The high purity aluminum plates were anodized in oxalic acid aqueous solution with variation of cell voltage. The pore size and interpore distance both increase with the applied potential. During the post treatment of barrier thinning, small-size pores with split-up structure at the tips are observed due to current-limited anodizing process (decreasing cell potential). The rectifying properties of the barrier layer allow the pores to be filled by nickel by AC electrodeposition. The nickel nanowires array shows the ferromagnetic properties with a preferred magnetic orientation along the wire axis. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.