3D distribution of magnetic CoNi alloy nanoparticles electrodeposited on vertically aligned MWCNT showing exceptional coercive field

Abstract

A novel, fast and simple method to achieve a 3D distribution of CoNi nanoparticles (NPs) by electrochemical deposition on vertically aligned multiwall carbon nanotubes is described. Alignment is maintained during the electrodeposition. This method allows to easily obtain magnetic anchored, no aggregation, nanoparticles spatially distributed almost homogenously in a thick 3D structure (10µm). Potential and charge of deposition condition size, composition and crystalline structure of the CoNi NPs and then the magnetic properties of the NPs/CNTs structures. The structures with hcp CoNi NPs of around 70nm obtained at low deposition potentials present an exceptional high coercive magnetic field (higher than 1kOe), never previously found for CoNi NPs. Structures with hcp+fcc CoNi NPs present lower coercivity, which corresponds to the lower magnetic anisotropy of the fcc crystalline phase.