Investigation on highly ordered porous anodic alumina membranes formed by high electric field anodization

A simple and cost effective method for fabricating long-range ordered porous anodic alumina (PAA) membranes is presented, which explores a self-ordering regime with controllable interpore distances over a large scale (300–360 nm). The cohesive force at the hemi-spherical scallop/cell wall (HS/CW) interface is weaker than the other locations. When the PAA membranes were immersed in H3PO4 solution, regular cheese-like hexagonal patterns have been propagated at the cell boundaries. With increased etching time, numerous pores were observed at triple points where three cells met. The distinct fracture and etching behaviors in PAA can be ascribed to the intense ionic transport accompanied by the volume expansion in the barrier region under high electric field.