Abstract Anodic Aluminum Oxide Research Articles

In vitro Biocompatibility Evaluation of Anodic Alumina Substrates with Electrochemically Embedded Silver

Anodic aluminum oxide films modified by silver incorporation (Al-O-Ag) under specific electrodeposition conditions were produced and their biocompatibility was analyzed by in vitro assays using mammalian cell lines. The results obtained demonstrate that Al-O-Ag substrates are well tolerated by human dermal fibroblasts. The alumina pads doped with silver for short time-period (30 seconds) showed the highest biocompatibility among all modified metal substrates and in comparison with three dental alloys.

Studies of mechanisms and characteristics of the fluorescence enhancement on anodic aluminum oxide thin film

Anodic aluminum oxide (AAO) thin film recently has been found as a new type of fluorescence enhancement nanomaterial. However, the mechanisms of the AAO thin film for the fluorescence enhancement have not been completely understood. Herein, the studies of its mechanisms are reported. Based on the experimental and modeling results, it has been found that the main contributing factor to the fluorescence enhancement is probably the plasmonic Al nanoparticles (NPs) embedded in the film, while the nanopore size and porosity of AAO thin film have a limited contribution. The characteristics of the enhancement have also been studied. It has been found that the enhancement is highly related to the gap between the fluorophore and the surface of the AAO thin film. Different excitation wavelength also results in different fluorescence enhancement. Using a simple model with a layer of Al NPs uniformly distributed in the thin film, the calculated enhancement factor of electric field and characteristics of the fluorescence enhancement match the experimental results.

Fabrication of Low Cost Membrane from Anodic Aluminum Oxide

Anodic Aluminum Oxide (AAO) membrane has been successfully fabricated from two-step anodization with aluminum low grade (Al6061). The pore density, the pore diameter, and the interpore distance can be controlled by varying anodization process conditions. However, there are limits to control the mechanical strength and growth of AAO arrays, such as pore density, pore diameter and interpore distance. In this research the self-organized two-step anodization is carried out varying time at 24, 48 and 72 hours, respectively with 40V at the low temperature 2-5°C. The optimum conditions of AAO with two-step anodization is 40V for 48 hr. Finally, AAO substrate is separated from aluminum low-grade and enlarged pore diameter with pore widening process by 5% H3PO4. The physical properties were investigated by mean of field emission scanning electron microscope (FE-SEM) show that the average pore diameter and average interpore distance increase with the anodization time. Al6061 Aluminum substrate can be used to fabricate a nanoporous AAO film with an average pore diameter and average interpore distance larger than 70 and 90 nanometers, respectively but less mechanical stability.

Controllable template approach for ZnO nanowire growth

Anodic aluminum oxide (AAO) is an optically transparent material with uniform hexagonal pores, which has widely been used as a template for nanowire growth. This study examines the potential of utilizing commercially available AAO to fabricate sub-10 nm ZnO nanowires by atomic layer deposition. The pore diameter of the AAO framework is reduced by controlled deposition of Al2O3. Subsequently, ZnO is deposited and ZnO nanowires are obtained. The analysis of structural and optical properties shows that the nanowires are polycrystalline, and exhibit a pronounced near band edge emission. Photoluminescence (PL) measurements are performed to monitor the effect of additional coating with Al2O3 and ZnO, on the optical stability of the AAO. The measurements indicate that the PL is highly influenced by the adsorption and desorption of species from the ambient at the surface. ALD deposition of a thin Al2O3 layer reduces considerably the effect of ambient atmosphere. The layer of Al2O3 facilitates PL characterization of very thin ZnO nanowires.

Nanoporous Anodic Aluminum Oxide (AAO) Thin Film Fabrication with Low-Grade Aluminium

Anodic aluminum oxide (AAO) is well known for its nanoscopic structures and its applications in microfluidics, sensors and nanoelectronics. The pore density, the pore diameter, and the interpore distance of an AAO substrate can be controlled by varying anodization process conditions. In this research, the self-organized two-step anodization is carried out with a low-grade (Al6061) aluminium substrate using a 40V voltage at the temperature of 2 to 5 °C. Three experiments are done with the anodization time of 24 hours, 48 hours and 72 hours. The structural features of AAO are characterized by a field emission electron microscope (FE-SEM). The data from FE-SEM show that the average pore diameter increases with the anodization time, and that the Al6061 aluminium substrate can be used to fabricate a nanoporous AAO film with an average pore diameter smaller than 17 nanometers.

Formation of Anodic Aluminum Oxide with Branched and Meshed Pores

Anodic aluminum oxide (AAO), with a self-ordered hexagonal array, is important for various applications in nanofabrication including as the fabrication of nanotemplates and other nanostructures. With the consideration, there have been many efforts to control the characteristic parameters of porous anodic alumina by adjustment of the anodizing conditions such as the electrolyte, temperature, applied potential, and Al purity. In particular, impurities in Al are changing the morphology of an alumina film; however, the formation mechanism has not yet been explained. In this work, we anodized a high purity (99.999%, Al(high)) and low purity (99.8%, Al(low)) aluminum foil by a two-step anodization process in an oxalic acid solution or phosphoric acid. It was found that the purity of aluminum foil has influenced the morphology of the alumina film resulting in branched and meshed pores. Also, electrochemical analysis indicated that the branched and meshed pores in the low-purity Al foil formed by the presence of impurities. Impurities act as defects and change the general growth mechanism for pore formation by inducing an electric field imbalance during anodization. This work contributes to the research field of topographical chemistry and applied fields including nanofabrication.

Simple fabrication of highly ordered anodic aluminum oxide (AAO) films

AbstractAnodic aluminum oxide is a well-known template for nanofabrication. Structural features of anodic aluminum oxide, such as pore diameter, can be controlled by adjusting anodization operating conditions. In this paper we will describe how nanoporous alumina of different porosities was prepared using electrochemical anodization. The influence of anodization time, potential, and temperature on the formation of well-ordered porous anodic aluminum oxide was studied. Results from high-resolution field-emission scanning electron microscopy have shown that pore diameter increases with increasing potential, temperature, and anodization time. Optimal anodic aluminum oxide pore diameter and arrangement were obtained for samples anodized at 40 V, 30°C for 60 min.

Fabrication and geometric characterization of highly-ordered hexagonally arranged arrays of nanoporous anodic alumina

Abstract Anodic aluminum oxide (AAO) has been fabricated in the 0.3 M oxalic acid at voltage range 20-60 V and temperature range of 35-50oC. The resulting nanoporous alumina surfaces were characterized by high resolution scanning electron microscopy, and the images were quantitatively analysed by means of an innovative approach based on fast Fourier transform. The influence of operating anodization voltage and electrolyte temperature on nanopores geometry (pore diameter, interpore distance, porosity, pores density) and arrangement has been studied in details and compared to literature data and theoretical calculations. It was found that independently from the temperature, the best arrangement of the nanopores is for anodic aluminum oxide formed at voltages ranging from 40 to 50 V. Moreover, it was found that pore diameter and interpore distance increase linearly with voltage, what is in line with the literature data.

Transformation of anodic aluminum oxide to nanoporous α-Al2O3, ruby and Ti-sapphire micropatterns

Abstract Anodic aluminum oxide (AAO) stands in the forefront of the most important materials in modern nanotechnology. Its regular nanoporous structure is widely used for template assisted nanopatterning, optical applications, membrane science and plenty more. Our study presents an enhancement on the potential application of AAO by exploiting its inherent nature of polymorphism. Amorphous AAO is selectively transformed to α-Al 2 O 3 by a laser-induced photo-thermal process. Carbon nanotubes (CNT) are employed as a sacrificial laser light absorber to accomplish the phase transformation of AAO to α-Al 2 O 3 . Doping of the evolving α-Al 2 O 3 with Cr or Ti enables preparation of free designable photoluminescent surface patterns. The superior properties of α-Al 2 O 3 are utilized to create hierarchically structured systems for optical, biomedical and lithographic applications.

Template method for fabricating interdigitate p-n heterojunction for organic solar cell

Anodic aluminum oxide (AAO) templates are used to fabricate arrays of poly(3-hexylthiophene) (P3HT) pillars. This technique makes it possible to control the dimensions of the pillars, namely their diameters, intervals, and heights, on a tens-of-nanometer scale. These features are essential for enhancing carrier processes such as carrier generation, exciton diffusion, and carrier dissociation and transport. An interdigitated p-n junction between P3HT pillars and fullerene (C60) exhibits a photovoltaic effect. Although the device properties are still preliminary, the experimental results indicate that an AAO template is an effective tool with which to develop organic solar cells because highly regulated nanostructures can be produced on large areas exceeding 100 mm2.

One-Step Anodization Preparation and Photoluminescence Property of Anodic Aluminum Oxide with Nanopore Arrays

Anodic aluminum oxide (AAO) film with nanopore arrays was prepared by one-step anodization of highly pure aluminum foil. Morphology, structure and photoluminescence property of AAO were characterized. Results showed that AAO owned honeycomb structure which was characterized by close-packed arrays of columnar hexagonal cells, each containing a central pore normal to the substrate. There were three peaks at around 370, 385 and 470 nm in the PL spectrum of AAO, which should be mainly attributed to the oxygen vacancies.

Fabrication of anodic aluminum oxide nanotemplate and investigation of their anodization parameters

Anodic Aluminum Oxide (AAO) nanotemplate, is a kind of layer made by anodizing a thin film of aluminum on a substrate. It contains alternate arrays and pores in the dimension of nanometer scale, which is currently being used to fabricate nano devices, magnetic nanostructures, polymeric nanowires, super conductors and nanofibers. This structure contains orderly columnar hexagonal porous cells. In this research, we have fabricated AAO nanotemplates on glass and pure aluminum substrate. In our research we have kept the temperature, concentration and voltage constant but the time was a variable. We observed that the dimensions of hexagonal pores increased with a linear speed of 100 nm per hour. Also the effect of annealing on the nanostructure is investigated. After analyzing annealed structure, it was observed that it is homogenous.

Completely Filling Anodic Aluminum Oxide with Maghemite Nanoparticles by Dip Coating and Their Magnetic Properties

Anodic aluminum oxide (AAO) nanotemplates were completely filled with maghemite (γ-Fe 2 O 3 ) nanoparticles by a dip-coating process and their magnetic properties were investigated. Maghemite particles with ―20 nm diameter and stabilized by oleic acid were selectively deposited into AAO pores with ∼100 nm diameter. The multiple layers of particles were obtained by repeating the procedures of dip coating and removing oleic acids from the particles. The magnetic moment of AAO with particles increased in proportion to the number of layers. These results demonstrate the possibility of integrating nanoparticles into nanotemplates and controlling their properties.

In Situ Template Synthesis of TiO<sub>2</sub> Nanotube Array Films

Anodic aluminum oxide (AAO) is commonly used as a starting template for fabrication of several kinds of functional nanoscale devices due to its homogeneous nanohole structure with high aspect ratio. In this paper, high density and uniform titanium dioxide nanotube array films were prepared via liquid phase deposition method by immersing the AAO templates in an aqueous ammonium hexafluorotitanate solution. The phase and microstructure of the nanotube array films were characterized by X-ray diffraction and field-emission scanning electron microscopy. It was found that the mean inner diameters of nanotube are 40-100 nm, mainly depended on different templates and post treatment condition; the phase of as-deposited TiO2 array film was amorphous, while it became anatase at above 400°C.