Nanoscale Topography: A Tool to Enhance Pore Order and Pore Size Distribution in Anodic Aluminum Oxide

Leitao, Diana C.; Apolinário, Arlete; Sousa, C. T.; Ventura, J.; Sousa, J. B.; Vázquez, M.; Araújo, João P.

doi:10.1021/jp202336j

Cited by 49 publications

(51 citation statements)

References 42 publications

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“…16 Prior to anodization, Al disks were cleaned in acetone and ethanol, and electropolished in a solution of 75% ethanol and 25% perchloric acid by applying 20 V for 2 min. 26 The subsequent anodization processes were performed in 0.3 M oxalic acid at 40 V, maintaining the electrolyte temperature at $4 C. To obtain ordered hexagonal nanopore arrays first anodizations were performed for 24 h. The alumina was then removed by chemical etching in an aqueous solution of 0.2 M H 2 CrO 4 and 0.4 M H 3 PO 4 at 60 C, and second anodizations were performed using the same conditions as the first ones, but only for $20 h, producing membranes with $ 50 lm in thickness. 22 The obtained NpATs had pore diameters of d $ 3564 nm and interpore distances of D int $ 10263 nm.…”

Section: Methodsmentioning

confidence: 99%

Magnetic interactions and reversal mechanisms in Co nanowire and nanotube arrays

Proença¹,

Sousa

Escrig

et al. 2013

Journal of Applied Physics

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Ordered hexagonal arrays of Co nanowires (NWs) and nanotubes (NTs), with diameters between 40 and 65 nm, were prepared by potentiostatic electrodeposition into suitably modified nanoporous alumina templates. The geometrical parameters of the NW/NT arrays were tuned by the pore etching process and deposition conditions. The magnetic interactions between NWs/NTs with different diameters were studied using first-order reversal curves (FORCs). From a quantitative analysis of the FORC measurements, we are able to obtain the profiles of the magnetic interactions and the coercive field distributions. In both NW and NT arrays, the magnetic interactions were found to increase with the diameter of the NWs/NTs, exhibiting higher values for NW arrays. A comparative study of the magnetization reversal processes was also performed by analyzing the angular dependence of the coercivity and correlating the experimental data with theoretical calculations based on a simple analytical model. The magnetization in the NW arrays is found to reverse by the nucleation and propagation of a transverse-like domain wall; on the other hand, for the NT arrays a non-monotonic behavior occurs above a diameter of $50 nm, revealing a transition between the vortex and transverse reversal modes. V C 2013 American Institute of Physics. [http://dx

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Section: Methodsmentioning

confidence: 99%

Magnetic interactions and reversal mechanisms in Co nanowire and nanotube arrays

Proença¹,

Sousa

Escrig

et al. 2013

Journal of Applied Physics

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“…This shallow ripple-like structure is an EP characteristic of metals 40 and can be used as a pre-pattern prior to anodization to obtain highly ordered oxide nanostructures, as shown in the case of Al. 36,40,[42][43][44][45] The electrochemical polishing of Ti is usually achieved in sulphuric acid-based electrolytes, which results in smooth surfaces. 46 However, in this work the EP conditions used (electrolyte type and voltage) resulted in organized dimple patterns, 40 with an interripple spacial period = 97 nm [ Fig …”

Section: Ti Surface Topography Analysesmentioning

confidence: 99%

“…[25][26][27] On the other hand, the pre-treatment of the initial metal foil was shown to be a simple and efficient method to induce a high degree of organization in AAO templates. 36 In the TiO2 NT array case, studies using pretreatments such as electropolishing (EP) or mechanical polishing (MP) indicated that a Ti smooth surface is crucial to obtain highly ordered NT arrays since it ensures a uniform electric field distribution over the Ti surface during the anodization. [27][28][29]37 In particular, Lee et al showed that a decrease of the surface roughness by EP leads to NTs with a more uniform length and a higher density, but almost no hexagonal NT domains were observed.…”

Section: Introductionmentioning

confidence: 99%

The role of the Ti surface roughness in the self-ordering of TiO₂ nanotubes: a detailed study of the growth mechanism

et al. 2014

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Highly ordered TiO2 nanotubes (NTs) were synthesized by electrochemical anodization of Ti foils. We investigated the effect of the Ti surface roughness (applying different pretreatments prior to the anodization) on the length, growth rate and degree of selforganization of the obtained NT arrays. The mechanisms related to the TiO2 NT formation and growth were correlated not only with the corresponding anodization curves but also with their appropriate derivatives (1 st order) and suitable integrated and/or obtained parameters, to reveal the onset and end of different electrochemical regimes. This enables an in-depth interpretation (and physical-chemical insight), for different levels of surface roughness and topographic features. We found that pretreatments lead to an extremely small Ti surface roughness, offer an enhanced NT length and also provide a significant improvement in the template organization quality (highly ordered hexagonal NT arrays over larger areas), due to the optimized surface topography. We present a new statistical approach for evaluating highly ordered hexagonal NT array areas. Large domains with ideally arranged nanotube structures represented by a hexagonal closely packed array were obtained (6.61 m 2 ), close to the smallest grain diameter of the Ti foil and three times larger than those so far reported in the literature. The use of optimized pre-treatments then allowed avoiding a second anodization step, ultimately leading to highly hexagonal self-ordered samples with large organized domains at reduced time and cost.

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“…Each Al foil was rinsed in acetone, ethanol and distilled water. Immediately prior to anodization, the Al foils were individually electropolished in a stirred 10 °C bath of perchloric acid, HClO4, and ethanol, C2H5OH, (volume ratio 1 : 4) at 20 V during 2 min, to reduce surface roughness and create nanopatterns for posterior pore nucleation [28]. Finally, the substrates were rinsed in ethanol, followed by deionized water and dried in air.…”

Section: Sample Preparation and Characterizationmentioning

confidence: 99%

Ultra-long Fe nanowires by pulsed electrodeposition with full filling of alumina templates

Azevedo¹,

Sousa²,

Ventura³

et al. 2014

Mater. Res. Express

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With the increasing demand for high quality methods for the fast fabrication of extremely high aspect ratio nanoparticles, the research for efficient, low-cost and simple techniques has become fundamental. A promising approach on the synthesis of these materials is here addressed. Pulsed electrodeposition in porous anodic alumina templates was improved enabling, for the first time, a simple and cost effective fabrication method for vertically aligned nanomaterials with aspect ratios never reported with this method. Iron nanowires were electrodeposited and the effect of electrolyte molar concentration, temperature and stirring, pulse shape and barrier layer thickness on the deposition quality was investigated to potentially increase the template filling and the nanowires length. The electro-deposition temperature and current density were also found to be determinant parameters affecting NWs crystallography. A methodology of surface response design of experiment was conducted to retrieve the optimum values for the deposition parameters. With the determined optimized process, we were able to obtain filling ratios up to 93% and aspect ratios over 10 times higher than previous reports for an alternating current method. The high deposition homogeneity combined with the simplicity of the pulsed deposition method, can open new opportunities for the nanofabrication of nanowires.

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Nanoscale Topography: A Tool to Enhance Pore Order and Pore Size Distribution in Anodic Aluminum Oxide

Cited by 49 publications

References 42 publications

Magnetic interactions and reversal mechanisms in Co nanowire and nanotube arrays

Magnetic interactions and reversal mechanisms in Co nanowire and nanotube arrays

The role of the Ti surface roughness in the self-ordering of TiO₂ nanotubes: a detailed study of the growth mechanism

Ultra-long Fe nanowires by pulsed electrodeposition with full filling of alumina templates

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Nanoscale Topography: A Tool to Enhance Pore Order and Pore Size Distribution in Anodic Aluminum Oxide

Cited by 49 publications

References 42 publications

Magnetic interactions and reversal mechanisms in Co nanowire and nanotube arrays

Magnetic interactions and reversal mechanisms in Co nanowire and nanotube arrays

The role of the Ti surface roughness in the self-ordering of TiO2 nanotubes: a detailed study of the growth mechanism

Ultra-long Fe nanowires by pulsed electrodeposition with full filling of alumina templates

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Product

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The role of the Ti surface roughness in the self-ordering of TiO₂ nanotubes: a detailed study of the growth mechanism