Abstract
Abstract Fabrication of one-dimensional nanowires has been researched for many years. Furthermore the multilayered nanowires were also synthesized to investigate their fundamental properties for various applications. By use of Anodic Alumina Oxide (AAO) as template, the nanowires synthesized by electrochemical method could be fabricated in large scale with low cost and high throughput. In this work, Ni/Au multilayered nanowires were synthesized by dual-bath method. Ni layers were deposited by electrodeposition and Au layers were produced by Galvanic replacement. The structures were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), and their magnetic properties were characterized by Vibrating Sample Magnetometer (VSM). The results shown that a sharp Ni/Au interface and regular structures with nanowire diameter of ca. 265 nm is obtained. The diffraction pattern of Ni layer indicated that the nanowires is polycrystalline structures. Magnetic measurement by VSM showed that easy-magnetic directions are dominated by shape anisotropy of Ni layers. Diffusion behavior between Ni/Au layers were also studied by annealing at high temperatures. X-Ray diffractometer (XRD) was used to identify the phases after annealing. The results showed that NiAu metastable phase appeared at 650 oC accompanying with NiO phase. The NiO is due to oxidation of Ni at high temperature during venting the chamber. Annealing at 750 oC caused agglomeration of Au atoms and the XRD cannot detect NiAu phase. Besides, the NiAu phase tends to separate at 750 oC. Magnetic measurement also showed a decrease of coercive field as the annealing temperature rises.