Fabrication Of Magnetic Nanowire Arrays By Electrodeposition Into Nanoporous Anode Alumina Oxide Template

With the development of electronic science and technology, highly ordered magnetic nanowire arrays have become an important part of one-dimensional nanostructural materials due to their attractive application in high-quality magnetic recording materials. Magnetic nanowire arrays can be fabricated by means of direct current (DC) electrodeposition using anode alumina oxide (AAO) template since this technique is usually much simpler and cheaper than other methods.In this paper, Co and Sm–Co nanowire arrays were prepared by DC electrodeposition method using AAO template in aqueous solution, and their structures, patterns, components and magnetic properties were characterized by X-ray power diffraction (XRD),field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM), respectively. The main work and conclusions are listed as below:1. The AAO templates were successfully fabricated by two-step anodic oxidation method. The parameters of AAO template such as diameter and orderliness of nanopores, porosity factor, straightness of porous channel and thickness of template can be changed by the changment of annealing statement, electrolyte and oxidation times. It is studied that the best fabrication process of AAO template is as follows: Aluminum foil (99.999%) was annealed at 500℃for 5h, and then two-step anodizing of aluminum was carried out under a constant cell voltage of 40V in a 0.3M oxalic acid solution, where the temperature was kept constant below 10℃.2. The Co nanowire arrays were prepared by AAO template successfully. The effect of voltage, pH value, solution concentration and heat treatment on structure and magnetic properties of Co nanowires were studied in the article. All of the Co nanowire arrays are not oxidated, confirming a dominant hexagonal closed packed (HCP) crystalline structure of Co with the preferred orientation. The nanowires show an obviously shape anisotropy, and the effective magnetic anisotropy is determined both by shape anisotropy and by magnetocrystalline anisotropy. The structure of the Co nanowire arrays can be changed by changing the experiment parameter, which can influence the magnetic properties immediately.3. The Sm–Co nanowire arrays were electrodeposited in the nanoprous of AAO template at the room tempreture from a chloride aqueous solution. The nanowires are amorphous with a uniform diameter. The discontiguous nanowires grow in the nanopores of AAO template, and the surface of the nanowires is not very smooth with hollows existing in part domains. Although the nanowires contain foreign element, Sm–Co nanowires contain substantial Sm element, the atomic ratio of which and Co element is 78.1:21.9.