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Self-organization of nano-holes in anodic aluminium oxide.

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Proud Mary

Sun Oct 04 2009, 10:46PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

1. Could anyone kindly explain in as simple terms as possible the principles underlying the self-organization of nano-holes in anodic aluminium oxide.?

2. Once the nano-holes have formed, are they of sufficiently small dimensions to limit the Brownian motion or even spin of further ions entering the nano-hole?

3. Is there any sense in which ions might have to queue up in order to enter the nano-holes?

4. When plating into the nano-holes with palladium, for example, how is the oxide matrix best removed without distressing the palladium nano filaments so formed.

To anyone who cares to help out with answers or explanations, do please remember that here, as elsewhere, I am profoundly half-educated, and am unlikely to understand anything much more than someone in special needs, so it may be that some of the questions themselves are gobbledegook, for which I ask ein wenig Verstehen, a little understanding.

Thank you in anticpation of your time,

Harry.

Bored Chemist

Mon Oct 05 2009, 05:47AM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Do you have a reference for this?
My guess would be they wash the Al2O3 away with NaOH.

Proud Mary

Mon Oct 05 2009, 06:22AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Hexagonal Arranged ZnO Nanowire Arrays by Using Au Nanohole Membranes as Fabrication Templates

H. J. Fan, W. Lee, K. Nielsch, M. Zacharias, A. Dadgar, A. Krost
Otto-von-Guericke-University, Magdeburg Germany

A new template method for large-scale fabrication of hexagonally patterned and vertically aligned ZnO nanowires is demonstrated. The process involves a novel type of metal membrane, a gold catalyst template produced using the membrane as deposition mask, and the catalyst-guided growth of ZnO nanowires. The metal membranes, composed of hexagonal nanohole arrays, are electrochemically replicated from ordered porous alumina. The ZnO nanowires obtained have a uniform alignment perpendicular to the GaN surface and a distribution according to the pattern defined by the nanohole membrane. Such periodically arranged ZnO nanowires have potential applications as sensor arrays and piezoelectric transducers.

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Electroplating of ZnO Nanowires Using Nanohole Arrays of Anodized Aluminum Oxide and Effects of Thermal Annealing

Ken-ichi Ogata, Shoso Shingubara, Hiromi Yorozu, Tadahiko Nakanishi

Electroplating of ZnO nanowires was conducted using gold embedded anodized aluminum oxide (AAO) films on Si substrates. For electroplating, insulating layers at the bottom of AAO nanohole structures need to be removed. After electroplating, hexagonal structure of vertical ZnO nanowires was observed, however, they were broken and lied down by thermal annealing process. Photoluminescence (PL) spectra were investigated and that of post annealed ZnO nanowires indicates that nitrogen atoms were incorporated as acceptor.

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Filling of FePt in AAO Nanohole Array by DC Pulsed Electrodeposition
H.Mori,T.Korenaga, N.Hosomi, *T.Terui, and Shingubara

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Highly Ordered Nanohole Arrays in Anodic Porous Alumina
in Nanostructure Science and Technology

Hideki Masuda

Anodic porous alumina with highly ordered structures could be formed based on two types of ordering processes: naturally occurring ordering under the appropriate anodizing conditions and anodization using pretextured Al. The fabrication based on the naturally occurring long-range ordering is simple and useful for the ordered hole array configuration with large area. Anodic porous alumina with an ideally ordered hole array obtained by the pretexturing process is useful for applications in which a strictly ordered single-domain hole configuration is required, such as optical devices or patterned recording media. Both types of ordered anodic porous alumina are promising as starting structures for the fabrication of a wide variety of functional devices with nanometre dimensions.

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Formation of unidirectional nanoporous structures in thickly anodized aluminum oxide layer

Hyun-Chae NAa, Taek-Jin SUNGa, Seok-Heon YOONa, Seung-Kyoun HYUNa, Mok-Soon KIMa,

Division of Materials Science and Engineering, Inha University, 253 Yonghyun-dong, Nam-gu, Incheon, 402-751, Korea
Received 18 June 2008;
accepted 10 March 2009.

Abstract

A series of anodic aluminum oxide(AAO) was grown on the commercially pure 1050 aluminum sheet by controlling electrolyte temperature (2â€“15 Â°C) and an odizing time (0.5â€“6 h), using a fixed applied current density of 3 A/dm2 in diluted sulfuric acid electrolyte. A crack-free thick AAO with the thickness of 105â€“120 Î¼m and containing unidirectional nano sized pores (average pore diameter of 5â€“7 nm) is successfully achieved in the specimens anodized for 2 h, irrespective of electrolyte temperature. When anodizing time reaches 6 h, very thick AAO with the thickness of 230â€“284 Î¼m is grown, and average diameter of unidirectional pores is in the range of 6â€“24 nm. The higher values in both the AAO thickness and pore diameter are attained for the specimens anodized at higher temperatures of 10â€“15 Â°C. A crack is observed to exist in the AAO after anodizing up to 4 h and more. A higher fraction (more than 9%) of the crack is shown in the specimens anodized at higher temperatures of 10â€“15 Â°C for 6 h and a considerable amount of giant cracks are contained.

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