The reported study aims to demonstrate the application of a simple technique, which is referred to as pressure differential injection, to prepare metallic nanowires. This technique relies on the difference in pressure between the inside of sealed nanochannels of an anodic aluminium oxide (AAO) substrate and the ambient atmosphere to inject a molten metal, which is previously deposited on the substrate, into the AAO pores. The application of this technique enabled the fabrication of nanowires in aluminium with diameters comprised between 55？nm and 65？nm. 1. Introduction Among the different structures, which have contributed to the advent of the field of nanotechnology, metallic nanowires have played an important role as these one-dimensional components typically exhibit very different physical properties in comparison to their bulk counterparts due to quantum confinement effects. Such characteristics are of specific interest to meet the demand for the development of future miniaturised systems such as electronic and optical devices. In particular, nanowires in aluminium represent a potential candidate technology for the development of high-density and high-resolution microelectronic systems and future energy storage devices [1]. Aluminium has the benefits of low melting point, chemical stability, ductility, good electrical conductivity, and reasonable cost. However, in order to enable further studies of the properties of such nanostructures as well as their scaled-up deployment in potential applications, it is important to ensure that their production can be carried out efficiently, reliably, and cost effectively. A number of techniques have been investigated for the synthesis of nanowires such as electrodeposition [2] and chemical vapour deposition [3]. While these fabrication processes enable the manufacture of nanowires in different materials, they have been reported to show a lack of reliability over the control of the uniformity and the length of the produced nanowires [4]. To overcome these issues, the pressure injection method has been utilised successfully to form nanowires in various metals such as bismuth (Bi) [4], tin (Sn) [5], and Al [6]. This method relies on injecting a molten metal into the pores of an anodic aluminium oxide (AAO) substrate. In order to fill the AAO channels, external pressure is required for overcoming the surface tension of the molten metal. The necessary pressure can be described by the well-known Washburn equation, which is expressed as follows: where is the pore diameter of the AAO substrate used, is the surface
References
[1]
J. Benson, S. Boukhalfa, A. Magasinski, A. Kvit, and G. Yushin, “Chemical vapor deposition of aluminum nanowires on metal substrates for electrical energy storage applications,” ACS Nano, vol. 6, no. 1, pp. 118–125, 2012.
[2]
S. Michotte, S. Mátéfi-Tempfli, and L. Piraux, “Current-voltage characteristics of Pb and Sn granular superconducting nanowires,” Applied Physics Letters, vol. 82, no. 23, Article ID 4119, 3 pages, 2003.
[3]
G. S. Cheng, L. D. Zhang, S. H. Chen et al., “Ordered nanostructure of single-crystalline GaN nanowires in a honeycomb structure of anodic alumina,” Journal of Materials Research, vol. 15, no. 2, pp. 347–350, 2000.
[4]
Y. Bisrat, Z. P. Luo, D. Davis, and D. Lagoudas, “Highly ordered uniform single-crystal Bi nanowires: fabrication and characterization,” Nanotechnology, vol. 18, no. 39, Article ID 395601, 2007.
[5]
C. Chen, Y. Bisrat, Z. P. Luo, R. E. Schaak, C.-G. Chao, and D. C. Lagoudas, “Fabrication of single-crystal tin nanowires by hydraulic pressure injection,” Nanotechnology, vol. 17, no. 2, pp. 367–374, 2006.
[6]
C. A. Huber, T. E. Huber, M. Sadoqi, J. A. Lubin, S. Manalis, and C. B. Prater, “Nanowire array composites,” Science, vol. 263, no. 5148, pp. 800–802, 1994.
[7]
C. J. Smithells and E. A. Brandes, Metals Reference Book, Butterworth-Heinemann, New York, NY, USA, 5fth edition, 1976.
[8]
Y. Lin, S. B. Cronin, O. Rabin, J. Y. Ying, and M. S. Dresselhaus, “Transport properties of Bi1-x-Sbx alloy nanowires synthesized by pressure injection,” Applied Physics Letters, vol. 79, no. 5, pp. 677–679, 2001.
[9]
Y. M. Lin, X. Sun, S. B. Cronin, Z. Zhang, J. Y. Ying, and M. S. Dresselhaus, “Fabrication, transport properties of Te-doped Bi nanowire arrays,” in Proceedings of the Materials Research Society Fall Meeting, vol. 582, no. 1–6, pp. H10–H13, Boston, Mass, USA, December 1999.
[10]
Z. Zhang, J. Y. Ying, and M. S. Dresselhaus, “Bismuth quantum-wire arrays fabricated by a vacuum melting and pressure injection process,” Journal of Materials Research, vol. 13, no. 7, pp. 1745–1748, 1998.
[11]
C. G. Kuo and C. G. Chao, “A novel method of centrifugal processing for the synthesis of lead-bismuth eutectic alloy nanospheres and nanowires,” The International Journal of Advanced Manufacturing Technology, vol. 32, no. 5-6, pp. 468–472, 2007.
[12]
D. D. Sung, M. S. Choo, J. S. Noh, W. B. Chin, and W. S. Yang, “A new fabrication method of aluminum nanotube using anodic porous alumina film as a template,” Bulletin of the Korean Chemical Society, vol. 27, no. 8, pp. 1159–1163, 2006.
[13]
G. D. Sulka and W. J. Stepniowski, “Structural features of self-organized nanopore arrays formed by anodization of aluminum in oxalic acid at relatively high temperatures,” Electrochimica Acta, vol. 54, no. 14, pp. 3683–3691, 2009.
