An Array of Concentric Composite Nanostructure of Metal Nanowires Encapsulated in Zirconia Nanotubes: Preparation, Characterization, and Magnetic Properties

Abstract

An array of highly ordered ZrO2 nanotubes has been prepared by a simple sol−gel method using the alumina membrane as a template. Furthermore, with use of this nanotube array with an alumina membrane support as a “second-order template”, the novel composite nanostructures of metal nickel- or copper-filled ZrO2 nanotubes have been synthesized by electrodeposition. TEM images show that these encapsulated metals present as continuous and uniform nanowires in each and all ZrO2 nanotubes. It is more important that the wall thickness of the ZrO2 tubules, and the different morphologies of the encapsulated metals (metal nanowires or nanoparticles) can be controlled by the template used and synthesis conditions. Magnetic measurements on the ordered array of a concentric composite of ZrO2 nanotubes/Ni nanowires reveal that the coercivities are Hc∥ ∼ 237 Oe and Hc⊥ ∼ 138 Oe, respectively, which exhibits enhanced coercivities by comparison with that of the bulk Ni.