Key role of longitudinal disarranged growth in porous anodic alumina: Crystallographic orientation

Abstract

Porous anodic alumina (PAA) is a typical template for electrochemical deposition. The longitudinal disarranged growth (LDG) in a PAA template directly causes a distortion of deposited nanomaterials. Crystallographic orientation is an important parameter of aluminum (Al) and its influence on PAA longitudinal growth is the key to high-quality PAA templates. In this study, PAA films prepared from polycrystalline pure Al foils were used to investigate the key effects of crystallographic orientation on PAA LDG. A spatial mapping relationship between crystallographic orientation and PAA morphology was built using a scratch marking method with a combination of electron backscatter diffraction and scanning electron microscopy. The results showed that PAA LDG manifested as LDG regions, whose size was positively correlated with grain boundary misorientation. The effect of misorientation on the LDG was explained based on the volume expansion model. This study contributed to a further understanding of the PAA longitudinal growth mechanism.