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Self-Ordered Anodic Aluminum Oxide Formed by H2SO4 Hard Anodization

Schwirn, Kathrin and Lee, Woo and Hillebrand, Reinald and Steinhart, Martin and Nielsch, Kornelius and Goesele, Ulrich (2008) Self-Ordered Anodic Aluminum Oxide Formed by H2SO4 Hard Anodization. ACS NANO, 2 (2). pp. 302-310.

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The self-ordering of nanoporous anodic aluminum oxide (AAO) in the course of the hard anodization (HA) of aluminum in sulfuric acid (H2SO4) solutions at anodization voltages ranging from 27 to 80 V was investigated. Direct H2SO4-HA yielded AAOs with hexagonal pore arrays having interpore distances Dint ranging from 72 to 145 nm. However, the AAOs were mechanically unstable and cracks formed along the cell boundaries. Therefore, we modified the anodization procedure previously employed for oxalic acid HA (H2C2O4-HA) to suppress the development of cracks and to fabricate mechanically robust AAO films with Dint values ranging from 78 to 114 nm. Image analyses based on scanning electron micrographs revealed that at a given anodization voltage the self-ordering of nanopores as well as Dint depend on the current density (i.e., the electric field strength at the bottoms of the pores). Moreover, periodic oscillations of the pore diameter formed at anodization voltages in the range from 27 to 32 V, which are reminiscent of structures originating from the spontaneous growth of periodic fluctuations, such as topologies resulting from Rayleigh instabilities.

Item Type:Article
Uncontrolled Keywords:anodic aluminum oxide; self-assembly; nanopores; membranes; hard anodization; templates; modulated pore structure
Subjects:Material Science > Nanofabrication processes and tools
Material Science > Nanostructured materials
ID Code:5907
Deposited By:IoN
Deposited On:29 Jul 2009 12:24
Last Modified:29 Jul 2009 12:24

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