Understanding and morphology control of pore modulations in nanoporous anodic alumina by discontinuous anodization

Authors

  • Abel Santos,

    1. Departament d'Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda Països Catalans 26, 43007 Tarragona, Spain
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  • Lukas Vojkuvka,

    1. Departament d'Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda Països Catalans 26, 43007 Tarragona, Spain
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  • María Alba,

    1. Departament d'Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda Països Catalans 26, 43007 Tarragona, Spain
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  • Victor S. Balderrama,

    1. Departament d'Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda Països Catalans 26, 43007 Tarragona, Spain
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  • Josep Ferré-Borrull,

    1. Departament d'Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda Països Catalans 26, 43007 Tarragona, Spain
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  • Josep Pallarès,

    1. Departament d'Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda Països Catalans 26, 43007 Tarragona, Spain
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  • Lluís F. Marsal

    Corresponding author
    1. Departament d'Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda Països Catalans 26, 43007 Tarragona, Spain
    • Phone: +34 977559625, Fax: +34 977 559605
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Abstract

Here, we report on an electrochemical approach so-called discontinuous anodization (DA) for controlling the generation of pore modulations in nanoporous anodic alumina (NAA) under self-ordering conditions. In this method, the anodization of aluminium is performed by voltage pulses under mild anodization regime and thermal-acidic conditions. Furthermore, we perform an exhaustive and systematic study about the relationship between the pore modulation morphology and the main anodization parameters (i.e. acid electrolyte temperature and relax time between consecutive voltage pulses). The generation mechanism of the pore modulations is associated with the formation of a gel-like layer under these thermal-acidic conditions and its subsequent detachment during the beginning of each voltage pulse. All this makes it possible to control the pore modulation morphology in NAA at will, what is crucial for developing new nanostructures with accurately controlled geometry for such purposes as nanofluidics, magnetic nanostructures, optical biosensors, templates, selective molecular separators and so forth.

original image

A three-dimensional network based on NAA with controlled geometry: The DA by voltage pulses under hydrothermal conditions yields an accurate control over the pore modulation morphology. Therefore, the structure of the resulting 3D-NAA network can be designed at will for later applications.

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