Tailoring the porous nanostructure of porous anodic alumina membrane with the impurity control

Comparative Study of Pore Characterizations of Anodized Al–0.5 wt.% Cu Thin Films in Oxalic and Phosphoric Acids

“…The stages of anodization were discussed extensively in our previous publications where they were categorized as: (I) formation of dense aluminum oxide, (II) pore nucleation and organization, (III) steady-state growth of pores (plateau) and (IV) Al consumption. [28][29][30] The sudden drops in the current density at the onset of anodization is attributed to the formation of thin barrier of alumina layer. However, similar drop at the end of the anodization process is due to the depletion of aluminum¯lm.…”

“…This observation might be, related to the oscillations and spikes observed while anodizing in phosphoric acid. 10,29,30 (Fig. 4) where poor nanopores arrangement accompanied by nanopores population in the grain boundaries was observed.…”

“…The phenomena and mechanism leading to the observed pore characteristic are extensively discussed in our previous publications. 10,[28][29][30][31]36…”

“…We have shown that the anodization of Al doped with Cu leads to the formation of controlled horizontal and vertical pores while¯shbone shape with branching pores is obtained when Al-containing Si is anodized. [22][23][24][25][26][27][28][29] Beyond the solubility limit of Si in sulfuric, oxalic or phosphoric acid, brittle thin¯lms are formed.…”

“…[7][8][9] In our previous study, we proposed a mechanism describing the formation of horizontal pores and established theoretical and experimental relations between the horizontal and vertical pores as in°uenced by temperature and concentration. 29,30 Despite these e®orts, the in°uence of these impurities on pore geometry has not been fully established. This paper, therefore, reports a comprehensive experimental study on the e®ects of Cu impurity on the geometry of the pore at di®erent anodizing conditions.…”