Unique AAO films with adjustable hierarchical microstructures

Abstract

Anodic aluminium oxide (AAO) films with novel nano-/submicron-/micron-porous hierarchical structures have been fabricated by using a simple anodization method.

A new self-ordering regime for fast production of long-range ordered porous anodic aluminum oxide films

“…1(c). In former studies, it was found that the adding of ethanol to the electrolytes is favorable for obtaining a higher U a under the same experimental conditions [45,[48][49][50]59,61,62], which agrees well with the results above. By further increasing the adding proportion of ethanol, a new CCSV process has also been realized for the production of long-range ordered porous AAO film in electrolyte of Electrolyte I: ethanol = 1: 0.33 ( Fig.…”

“…In other words, U b are always greater than U a during these constant-current U aincreasing processes. In these cases, the CCSV processes are not necessary for obtaining uniform barrier layer with high enough U b , which further confirms that the adding of ethanol will make anodization processes more stable [45,[48][49][50]59,61,62]. It can be concluded that the equilibrium U a of CCSV processes increases with the proportion of ethanol adding, thus forming long-range ordered porous AAO films with controllable D int of 307-415 nm.…”

“…1(b) and (c)). In fact, the dynamic equilibrium between the oxidation and dissolution process is more difficult to be established under a comparatively higher U a for a given set of anodization conditions [24,[42][43][44][45][46][48][49][50]. Therefore, the more apparent oscillation of U a during the second CCSV process (∼166 V) can be reasonably explained.…”

“…A more obvious oscillation of U a can be observed under the second CCSV process (∼166 V). Considering that both of U a and J a can directly influence the microscopic morphology and structural parameters of porous AAO films to a large extent [16,21,22,24,29,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][53][54][55][56][57][58][59][60], the porous AAO film fabricated by CC anodizaiton process with a more stable U a will have a better cell ordering and uniformity ( Fig. 1(b) and (c)).…”

“…In this case, a constant-current voltage-increasing process is usually needed instead of applying the target U a directly [44,[48][49][50]. Fig.…”