Fabrication of Crystallized Porous Anodic Aluminum Oxide under Ultra-High Anodization Voltage

Porous anodic aluminum oxide (PAAO) films have attracted increasing attention due to their widespread applications as porous templates. In fact, PAAO films fabricated using high-voltage anodization have apparent advantages which include large-range tunable interpore distance, less impurities, and diverse microstructures. Finding the proper methods to explore the maximum anodization voltage and to analyze related mechanisms is important. Here, crystallized PAAO films with novel microstructures have been fabricated under ultra-high anodization voltage of 700-1000 V in ethanol-oxalic electrolyte system. The unique microstructure and composition of the prepared PAAO films have been studied by using characterization methods of scanniong electron microscopy and X-ray diffraction. Some important phenomena become more obvious under extreme experimental conditions, thus a better understanding of related intrinsic mechanisms of aluminum anodization can be achieved.