| One-dimensional nanowire arrays,due to their wonder physical and chemical properties,have great potential applications in many domains.AAO template was prepared by simple technics.In addition,the pore diameter is controllable in accordance with practical needs,so one-dimensional nano-arrays synthesized by AAO template has many studied deeply in these years,one-dimensional nano-arrays has been fabricated in the pores of the AAO template.The main contents as following:Firstly,AAO templates,with highly ordered hexagonally honeycomb arranged porous, were prepared by two-step anodic oxidation in 0.2M sulfuric acid and 0.3M oxalic acid, the surfaces of the AAO templates were characterized by SEM and AFM respectively,the phase structures of the templates were characterized by X-ray Diffraction(XRD). Hexagonal close-packed arrays of nanopores with a density of 1010～1011个/cm2,the phase structures of the templates is amorphous.Secondly,Ni nanowire arrays compounded with Zn were fabricated in AAO templates. The structure and the images of Ni/Zn nanowires are studied by XRD,SEM and TEM. From the image we can see that the nanowire arrays compounded have almost identical diameters of 90 nm and length of about 10μm.The results indicate that the isolated nanowires to have polycrystalline structure,the phases of them changed with the deposition potential and the nanowire arrays have a preferred orientation along[111]direction,the amount of deposited zinc in the nanowires increases with the increasesing deposition potential,whereas the amount of nickel decreases.Consequently,we can conclude that the texture configuration of binary alloy nanowire arrays can be adjusted by changing the deposition potential.In particular,the deposition of cations Zn into the alumina template will accelerate with increasing deposition potential.At last,Vibrating Sample Magnetometer(VSM) is employed to study the magnetic properties of the nanowires.The nanowire arrays there is no apparent magnetic anisotropy deposited at low potential.Thus,nanowire arrays show apparent magnetic anisotropy with the increasing potential,which may be due to structural changes caused by the increased concentration of zinc in the nanowires.The values of Hc∥and Hc⊥show different variations as functions of the deposition potential.When the external field is parallel to the long axis of the nanowire,the coercivity first increases with increasing deposition potential to a maximum at -1.35 V and then decreases sharply.The enhanced coercivity Hc∥of the NiZn nanowires array may be attributed to the high concentration of defects into NiZn nanowires and the additional contribution of magnetocrystalline anisotropy,caused by zinc doped in the nickle nanowires.However,the content of Zn in the nanowire increases with the deposition potential,and according to the phase diagram of the binary Ni-Zn system,a mixed structure of fcc and hcp phases will be formed in NiZn alloy.When the potential is higher than -1.35V,Zn atoms will be the main component of the nanowires,as demonstrated by XRD.Hc∥then decreases.On the other hand,Hc⊥decreases monotonically with increasing deposition potential.As with the anisotropy,the coercivity differences in different nanowires are thought to be caused by factors such as competition between shape anisotropy and magnetocrystalline anisotropy,the crystalline structure and local morphological changes in the nanowires. |
