## 3 Results and Discussion
### Fabrication and Characterization of AAM
It means that the increase in Al(OH)\({}_{3}\) concentration from 0.04 M to 0.095 M promotes the formation of more compact porous layers with narrower pores, in accordance with the solubility decrease whose trend is shown in Figure 2. As the passed charge was increased from 20 to 160 C cm\({}^{-2}\) in 0.4 M H\({}_{3}\)PO\({}_{4}\) and 0.095 M Al(OH)\({}_{3}\), the inner surface shows identical morphology with the same cell density of 6.52 x 10\({}^{12}\) m\({}^{-2}\), while the outer surface discloses a non-uniform distribution of circular pores a few of which ellipsoidal. Figure 2: Aluminum anodization in mixed 0.4 M H\({}_{3}\)PO\({}_{4}\)/Al(OH)\({}_{3}\) electrolytes at 160 V and 0 \({}^{\circ}\)C after 160 C cm\({}^{-2}\) vs. Al(OH)\({}_{3}\) concentration: (**a**) mol cm\({}^{-2}\) of Al oxidized as Al\({}_{2}\)O\({}_{3}\) and PAA moles cm\({}^{-2}\) formed; (**b**) anodizing % efficiency. Table 1 gives an overview of the influence on PAA morphological features of bath composition and electrical charge passed during aluminum anodizing at 160 V and 0 \({}^{\circ}\)C. The pore mean diameter of PAA formed in 0.4 M H\({}_{3}\)PO\({}_{4}\) and 0.095 M Al(OH)\({}_{3}\) after passing 160 C cm\({}^{-2}\) is 104 \(\pm\) 5% nm, a value far higher than the 51.68 \(\pm\) 5% nm evaluated at 20 C cm\({}^{-2}\) in the same anodizing conditions. Hence, Table 1 evidences that the increase in both charge passed and Al(OH)\({}_{3}\) concentration have the opposite effect because the first one promotes pore enlargement, while the second one favors pore narrowing. Figure 5 more clearly shows such behavior since it is possible to draw valuable information by the slopes of the curves. Figure 5a shows that the curve at 160 C cm\({}^{-2}\) is more sloping than those at lower charge density. This means that the longer time in solution greatly affects the decrease in pore size. It is also interesting to observe that the pore size of the PAA layers formed at 160 V in 0.4 M H\({}_{3}\)PO\({}_{4}\) and 0.13 M Al(OH)\({}_{3}\) are practically identical, independently of the charge passed. Such an effect is confirmed by Figure 5b, showing that pore population increases with Al(OH)\({}_{3}\) concentration up to about 0.095 M, then it sharply decreases to 0.13 M Al(OH)\({}_{3}\) where the pore population values are practically identical for all passed charges. Figure 3: Top views of PAA formed in 0.4 M H\({}_{3}\)PO\({}_{4}\) and 0.04 M Al(OH)\({}_{3}\) at 160 V and 0 \({}^{\circ}\)C: (**a**) and (**b**) inner, and outer surface at 20 C cm\({}^{-2}\), respectively; (**c**,**d**) inner, and outer surface at 160 C cm\({}^{-2}\), respectively. The slopes of the curves of Figure 5a evidence that the progressive decrease in the pore size with Al(OH)\({}_{3}\) concentration is much greater at 160 C cm\({}^{-2}\) (about 69.2%), while it is slight at 20 C cm\({}^{-2}\) (about 38.5%). On the contrary, the pore population decreases by 49% from 0.0 M to 0.13 M Al(OH)\({}_{3}\) at 20 C cm\({}^{-2}\), while an increase of about 15% was found in the same concentration interval for sample anodized at 160 C cm\({}^{-2}\). Moreover, Figure 5b shows that the pore population decreases as the passed charge increases from 20 to 160 C cm\({}^{-2}\) at constant Al(OH)\({}_{3}\) concentration with the exception of 0.13 M, where the pore population values are similar, practically.