Self-ordered anodic aluminum oxide formed by H2SO4 hard anodization
| Autor: | Martin Steinhart, Reinald Hillebrand, Ulrich Gösele, Kornelius Nielsch, Woo Lee, Kathrin Schwirn |
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| Rok vydání: | 2009 |
| Předmět: |
Materials science
Scanning electron microscope Macromolecular Substances Surface Properties Oxalic acid Molecular Conformation General Physics and Astronomy chemistry.chemical_element Nanotechnology chemistry.chemical_compound Aluminium Hardness Tensile Strength Materials Testing Aluminum Oxide General Materials Science Particle Size Electrodes Nanoporous Anodizing General Engineering Sulfuric Acids Electroplating Nanostructures Nanopore chemistry Chemical engineering Electrode Crystallization Current density |
| Zdroj: | ACS nano. 2(2) |
| ISSN: | 1936-086X |
| Popis: | 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 D(int) 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 D(int) 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 D(int) 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. |
| Databáze: | OpenAIRE |
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