Tailored Shapes of Fe-Ni-Co Nanowires

Abstract

Template-assisted, electrodeposited Fe-Ni-Co nanowires are reported targeting an Invar-like composition (e.g. Fe-rich, with < = 5 wt % Co) of interest for the materials low thermal expansion property and its ability to be magnetically aligned. The morphology of the nanowires is controlled by pulse and DC deposition conditions, and the electrolyte pH. Not only are nanotubes and solid wires fabricated, but also novel porous structures. The porous nanowires utilize the gas evolving side reaction as a dynamic template. Post treatment of nanowires via chemical etching, can also be used to shape the nanostructures. Two different approaches are examined, 1) creating dissimilar crystalline structure within the nanowire by the choice of the deposition operating conditions followed by a select etch in structure, and 2) introducing a sacrificial element, such as Cu, to selectively etch it in a passivating Fe-Ni-Co environment. Unique thinned nanowires and nanotips were designed. The authors acknowledge the NIH and Roche Diagnostics for support of this project.