Influence of Sulfur Incorporation into Nanoporous Anodic Alumina on the Volume Expansion and Self-Ordering Degree
Date of Issue2015-11-12
School of Physical and Mathematical Sciences
Self-ordering degree of anodic alumina nanopores is related to the volume expansion of the aluminum oxide. However, little is known about how the ionic species derived from electrolyte affect parameters inducing self-ordering of the nanopores. The influence of sulfur incorporation into nanoporous anodic aluminum oxide (AAO) films on volume expansion and self-ordering degree has been investigated under potentiostatic conditions (14–25 V) in different sulfuric acid electrolytes (3–20 wt %), the average current densities of each anodization being in the range of 0.1–10 mA cm–2. Rutherford backscattering spectroscopy (RBS) reveals that the incorporation of sulfur species into AAO, as well as the volume expansion factor (VEF), follows a logarithmic dependence on the average current density regardless of the applied voltage and sulfuric acid concentration. The relationship between volume expansion and the S/Al ratio is linear for each concentration of acid in the electrolyte. Furthermore, self-ordering regimes are also revealed for each acid concentration at VEF in the range of 1.50–1.66. We suggest that plasticity, enhanced by sulfur incorporation, counterbalances the high mechanical stress generated by volume expansion, thus inducing new self-ordering regimes. These new regimes are dependent not only on VEF but also on a subtle equilibrium between stress and plasticity of the nanoporous AAO films.
The Journal of Physical Chemistry C
© 2015 American Chemical Society. This paper was published in The Journal of Physical Chemistry C and is made available as an electronic reprint (preprint) with permission of American Chemical Society. The published version is available at: [http://dx.doi.org/10.1021/acs.jpcc.5b06928]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.