Effects of anodizing conditions on anodic alumina structure

In this paper, two-step anodization was used to obtain porous anodic alumina (PAA) films, which are widely used as the temples to fabricate nanomaterials. Effects of anodizing conditions such as anodizing voltage and the concentration of electrolyte on steady current density (Is) and anodic alumina structure were investigated for oxalic acid as an electrolyte. The result shows that Is is dependent on anodizing voltage exponentially. The relationship between the concentration of electrolyte and the pore diameter is almost linear, while there is no effect on inner-pore distance. At different anodizing voltage, the effect degree of the concentration of oxalic acid on the pore diameter is various. In oxalic acid electrolyte with given concentration matching with a specifically anodizing voltage, optimal nano-pores arrangements can be obtained. The higher voltage induces the collapse of thin inner wall and disordered alumina nanowires (ANWs) were formed.