Context:

Nanoporous anodic alumina is a material of great interest due to its low density, high aspect ratio, and because it is possible to obtain highly ordered structures from it. In the last decades, researchers have focused on controlling the morphological characteristics of fabricated porous structures, particularly regarding their ordering. Recently, characterization of the ordering of these structures has started to migrate from qualitative to quantitative methods, leading to the development of more precise characterization tools.

Method:

In this work, the ordering of the nanoporous anodic alumina (NAA) fabricated in oxalic acid 0,3 M was evaluated. Fast-Fourier transform was used to analyze the effect of anodizing potential in porous ordering. The regularity ratio was calculated based on the Fast-Fourier-transformed images generated from the top scanning electron microscopy (SEM) images of the obtained NAA samples.

Results:

It was observed that increasing the anodizing potential decreases the regularity ratio for the evaluated potentials. Additionally, it was found that morphological characteristics such as pore diameter and interpore distance increase with the anodizing potential.

Conclusions:

Highly ordered structures can be obtained through pure aluminum anodizing in 0,3 M oxalic acid at 40 V, 50 V, and 55 V. The regularity ratio is a useful instrument for the quantitative characterization of the ordering level of NAA structures. The NAA ordering level can be related with its properties, and then with NAA applications. The understanding of the anodizing potential effect on porous alumina ordering provides tools to improve the design of NAA-based devices.

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