Research On Morphology And Properties Of Dy-Ni Alloy Nanotubes/Nanowires Fabricated By Dc Electrodeposition Into The Template

Since nanometer materials were successfully fabricated in the 1980s,researchers had begun to notice the promising future of these materials.Owing to its outstanding properties and extensive application,the research upsurge of nanometer materials is still going on in recent years.One of the most popular nanomaterials is the nanomagnetic material,which can be widely used in many domains,such as magnetic recording,sensors,magnetic resonance imaging contrast agent,magnetic hyperthermia,physical separation and purification and so on.Moreover,one-dimensional nanomagnetic materials benefiting from their single magnetic domain structure and high coercivity are expected to get a new breakthrough in such areas as magnetic recording,magnetic liquid,electroacoustic device,damping device,lubrication and ore beneficiation.As we know,the rare earth elements have unique orbital characteristics.Both the orbital moment of atom and the spin torque of atom can contribute to magnetic moment.Therefore,the best permanent magnet alloys can be synthesized with some of the rare earth metals and the ferromagnetic metals.Thus the fabrication of one-dimensional magnet alloy materials containing rare earth element with proper size and properties is still one of the important content in the nanomaterial area nowadays.In our research,Dy-Ni alloy nanotubes/nanowires were eletrodeposited into anodic aluminum oxide(AAO)template from an acidic electrolyte.Their morphology and properties were studied in the paper.Then we also discussed the influence of annealing temperature on the samples.To get AAO templates with desired aperture and thickness,we firstly studied the influence of the preparation condition on the aperture and thickness of AAO template.The study indicated that the bearizing time significantly affects the aperture of the AAO template and the thickness of AAO template is significantly influenced by the second oxidation time.In the paper,the AAO templates were prepared in the same condition,in which the bearizing time,the first and second oxidation time were,respectively,bout 6 hours,12 hours and 45 hours.The SEM images showed that the aperture and the thickness of our AAO template were about 60nm and 50μm respectively.Moreover,we discovered that if the AAO membranes were prepared at too long second oxidation time,the hole of the membranes may warp partly.Also,too long bearizing time can lead to the holes of the AAO template feeding through.Under our oxidation condition,it can do a favor to the electro-deposition of the one-dimensional materials into the AAO template to control the second oxidation time ranging from 15h to 18h.The Dy-Ni alloy nanotubes/nanowires were synthesized in different deposition condition.Their morphology,element,structure properties and magnetic properties were studied according to SEM test,XRD test,EDS test,TEM test and PPMS test in the paper.We found that the structure and magnetic properties were obviously influenced by the deposition potential and the proportion of dysprosium ion and nickel ion in the electrolyte.The different deposition potential and different proportion of dysprosium ion and nickel ion in the electrolyte both lead to the different content of dysprosium and nickel in the DyNi alloy nanotubes/nanowires.With the increase of the absolute value of deposition potential or the augment of the dysprosium ion in the electrolyte,the content of dysprosium element increased and vice versa.Then the structure and magnetic properties were affected.In addition,the research of the magnetic property of our samples indicated that our Dy-Ni alloy nanotubes/nanowires had strong magnetic anisotropy,which could be mainly due to the crystal structure which can contribute to the magnetocrystalline anisotropy and the high aspect ratio which can contribute to shape anisotropy.As-prepared samples also were annealed in different temperature.The results indicate that the annealing process could affect both the structure properties and the magnetic properties of our Dy-Ni alloy nanotubes/nanowires.We found that proper annealing temperature could turn amorphous structure to crystal structure and increase the kind of crystal face.The research also showed that the coercivity,the saturation magnetization and the residual magnetization can all be improved by annealing process.