Morphology And Properties Of Gd-Co Nanotube/Wire Arrays Prepared By Electrodeposition Methods

Because nanotubes and nanowires have the unique structure and properties, in recent years they have gradually become the important study in the field of materials, chemistry, and electronics. The controllable preparation and the research on nanotubes and nanowires become difficulty due to their unique structure. Since the anodic aluminum oxide template (AAO) has advantages of well-ordered pore, simple preparation and low-cost, it has been widely used in research. As a fast, easy to operate, efficient, repeatable method of synthesis, electrochemical deposition with its unique advantages becomes an effective way for the preparation of nanomaterials and has great prospects.In this paper, Gd-Co nanotubes and nanowires with a uniform diameter are fabricated into AAO template by using direct current chemical deposition method. The morphology of samples is characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), and the compositions are confirmed by energy dispersive spectrometry (EDS). The crystalline structure is measured by X-ray diffraction (XRD) and selected area electron diffraction (SEAD). Finally, the magnetic properties of nanotubes and nanowires obtained under various conditions are tested at room temperature by comprehensive physical property measurement system (PPMS).In the experiment, AAO templates are obtained by a two-step anodization method from high purity aluminum foil. The pore size of AAO template is controlled by changing the type and concentration of the oxidizing solution, the first oxidation time and expanding aperture time. The thickness of the template is controlled by changing the secondary oxidation time.In the paper, Gd-Co nanotubes and nanowires are obtained by using home-made templates and business templates respectively, which are mostly mixed. By changing the aperture size of the template, the solution concentration and deposition voltage, we find that the smaller the aperture size is and the larger the solution concentration is, the easier it is to come into being nanowires; otherwise it is easy to obtain nanotubes. EDS analysis determines nanowires/tubes is composed of Gd and Co components. XRD and TEM measurements show nanowires/tubes is amorphous structure before annealing and they form a polycrystalline structure after re-crystallization annealing. The magnetic properties measurements indicate the direction of the easy magnetization axis of Gd-Co nanotubes is changed into the direction perpendicular to the nanotubes from parallel to the nanotubes with the decrease of deposition voltage. The deposition rate increases as the deposition potential decreases, so the length of nanotubes becomes large in the same deposition time. At the same time the content of Gd increases with decreasing the deposition potential. Thus the magnetostatic coupling between Gd-Co nanotubes increases and eventually exceed the magnetocrystalline anisotropy. After annealing the nanotubes are crystallized and magnetic properties of the nanotubes improve. Moreover as the annealing temperature increases, the coercive force and saturation magnetization become larger.