Relationship between pore diameter to cell diameter ratio and self-ordering of anodic porous alumina

Self-ordering behavior of anodic porous alumina formed in sulfuric acid, oxalic acid and phosphoric acid solutions was investigated. Domains of ordered cell array appeared following an exponential current increase with the increase in anodizing voltage. Concurrently, the ratio of pore diameter to cell diameter lowered to approximately 0.3, that was corresponding to a porosity of 0.1, regardless of electrolyte type when the voltage approached to the established individual self-ordering voltage. Mechanism of self-ordering is assumed to be closely related to the electric field strength at the porous film growth.