Fabrication and characterization of highly ordered porous alumina templates by a two-step anodization process. C. A. León-Patiño a , E. A. Aguilar-Reyes b , C. Ruiz-Aguilar c Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo Ed. “U”, Ciudad Universitaria, Morelia Mich., Mexico a caleon@umich.mx, b aareyes@umich.mx, c ziru_3@hotmail.com Keywords: anodic alumina, porous templates, anodization, nanopore, auto-ordered structure Abstract. Highly ordered through-hole anodic porous alumina membranes were fabricated by electrochemical oxidation of aluminum in a controlled two-step process. A teflon dispositive was used to ensure single side anodization. Under the most appropriate condition for the fabrication of ideally ordered anodic aluminum oxide (AAO), the voltage used was 15 V during 24 h in a 15 % w/v sulfuric acid solution. SEM, TEM and FESEM characterization shows that the as-fabricated AAO film has a defect-free array of straight parallel channels perpendicular to the surface. The thickness of the porous membrane is 20 microns, approximately. The ordered channels are formed in a honey comb arrange with a pore diameter in the range 20-30 nm, wall thickness of 10-20 nm, interpore distance of ∼40 nm, and high aspect ratio of 850. The pore density, quantified by image analysis, is 5.4×10 10 pore/cm 2 ; perfect ordering was maintained in the full depth of the membrane. Dimensions of this porous structure provide a convenient way to precision engineer the nanoscale morphology. Introduction Anodic aluminum oxide (AAO) is a self-organized nanostructured material containing a high density of uniform cylindrical pores that are aligned perpendicular to the surface of the materials and penetrate its entire thickness. In recent years, electrochemical processes have been widely used to fabricate materials with nanostructured arrangements. Their miniaturizing capacity and attractive structure made them suitable for new areas of applications in the fields of nanofilters [1], magnetic storage [2], solar cells [3], metal and carbon nanowires [4], and catalysis [5]. Given the uniformity of the porous channels and capacity to tailor their aspect ratio, the AAO templates with high pore densities are more versatile and economical than those obtained by sophisticated methods as lithography. The porous alumina nanostructures obtained by electrochemical oxidation of aluminum are sensible to experimental parameters as temperature, voltage, type and concentration of the electrolyte, and anodization time [6]. Since during the anodization process the aluminum film is immersed and exposed in its entire surface to the electrolyte solution, the dense aluminum oxide that results of the electrochemical reaction is trapped in the middle part of the membrane when the porous structures grow in opposite directions in both sides of the membrane [6-8]. This mechanism prevents to obtain open and continuous pores along the thickness of the membranes. The present work propose the synthesis of highly ordered through-hole anodic porous alumina membranes by a two-step anodization process of aluminum in sulfuric acid using a teflon dispositive specially designed to ensure single side anodization. The structure parameters of the resulting porous AAO membranes are studied by image analysis using different microscopy techniques. Experimental Procedure Synthesis of the auto-ordered AAO membranes. The porous AAO membranes were synthesized by a two-step aluminum anodization process. It started from ultra-high purity aluminum films (Alfa Aldrich, 99.9%, 100 µm thickness), which were sectioned in specimens of 1.5×1.5 cm for the anodes; the anodized area was 1×1 cm. As the cathode, it was used 6061 commercial aluminum film. Both electrodes were welded to aluminum extension wires of 1/32 inch to be connected to a Materials Science Forum Vol. 755 (2013) pp 75-81 Online available since 2013/Apr/24 at www.scientific.net © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/MSF.755.75 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 189.168.211.238, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico-10/02/14,04:58:51)