Article abstract

Nature Materials 5, 741 - 747 (2006)
Published online: 20 August 2006 | doi:10.1038/nmat1717

Subject Categories: Nanoscale materials | Porous materials | Surface and thin films | Design synthesis and processing

Fast fabrication of long-range ordered porous alumina membranes by hard anodization

Woo Lee, Ran Ji, Ulrich Gösele & Kornelius Nielsch

Nanoporous anodic aluminium oxide has been widely used for the development of various functional nanostructures. So far these self-organized pore structures could only be prepared within narrow processing conditions. Here we report a new oxalic-acid-based anodization process for long-range ordered alumina membranes. This process is a new generation of the so-called 'hard anodization' approach that has been widely used in industry for high-speed fabrication of mechanically robust, very thick (>100 mum) and low-porosity alumina films since the 1960s. This hard anodization approach establishes a new self-ordering regime with interpore distances, (Dint)=200–300 nm, which have not been achieved by mild anodization processes so far. It offers substantial advantages over conventional anodization processes in terms of processing time, allowing 2,500–3,500% faster oxide growth with improved ordering of the nanopores. Perfectly ordered alumina membranes with high aspect ratios (>1,000) of uniform nanopores with periodically modulated diameters have been realized.

  1. Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany

Correspondence to: Woo Lee e-mail:


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