Fabrication of highly ordered nanoporous alumina membranes: Probing microstructures by SAXS, FESEM and AFM

In this study, we report synthesis of highly ordered self-organized nanoporous alumina membranes (NAMs) with two distinct pore diameter ranges by two step anodization technique from two different electrolytes containing simple H2SO4 and mixed electrolyte consisting of H2SO4 and ethylene glycol. Three different complimentary techniques field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and small Xray scattering (SAXS) were used to characterize the synthesised membranes. An attempt was made to correlate the pore parameters obtained from low ensemble size two dimensional FESEM and AFM micrographs and from large area three dimensional scattering using SAXS. A special attention was given in estimating the porosity of these ordered membranes and compared the results. It was demonstrated that such controlled synthesis method can result in improved pore regularity in NAMs along with enhanced porosity, greater than 40%.