Preparation And Magnetism Of Quasi-One-Dimensional Metal And Ferrite

Recently,plenty of efforts have been expended on the synthesis of nanoscalematerials with the fast development of nanometer science and technology.Quasi-one-dimensional nanostructural materials have attracted much interest due totheir enriched properties and potential applications in optics and electronics.From thepoint of getting new materials and using their versatile properties,we havesuccessfully fabricated the CoFe₂O₄,ZnFe₂O₄,Fe nanotubes by sol-gel templatemethod and CoZn,FeZn,Fe,CoFe₂O₄ by electrochemical deposition template methodin the pores of porous anodic aluminum oxide(AAO).The main works and results are as follows:1.ZnFe₂O₄,CoFe₂O₄ nanotube arrays with the homogeneous thickness of tube wall inpolycrystal structure have been successfully fabricated by an sol-gel AAO template.The result indicates ZnFe₂O₄ nanotube arrays show typical superparamagnetism atroom temperature,which is different from the bulk ZnFe₂O₄.Owing to have the highmagnetocrystalline anisotropy,magnetic property of CoFe₂O-4 nanotubes is similarwith the magnetic property of CoFe₂O₄ particles.2.Ordered Fe nanotube arrays with an outer diameter of 50 nm and the tube wall of 15nm have been prepared in AAO template using an improved sol-gel reductionapproach.The sample has obvious magnetic anisotropy in cnotrast to CoFe₂O₄nanotubes.The result of MS indicates that the distribution of the moments in thetube is not random but a component of the magnetic moment arrangement is parallelto the tube axis.3.Highly ordered CoZn,FeZn alloy nanowire arrays with the diameter 40 nm and theaspect ratio of 75 have been prepared by AAO template electrodeposition technologyWhen the content of Zn is low,nanowire arrays show ordered structure and theorientation of (110) is preferred.With the increasing of Zn content in nanowires,anamorphous structure is formed.4.We have prepared highly ordered cobalt ferrite arrays in different diameter.Theinfluence of diameter,annealing temperature,and the ratio of Co²⁺ and Fe²⁺ to thestructure and magnetic properties of cobalt ferrite arrays are investigated.The results indicated that cobalt ferrite arrays with a preferred crystallite orientation and auniaxial magnetic anisotropy under the annealing temperature 430℃.We proposedthe growth mechanism of ordered crystal under confined spaced.5.Fe nanowire arrays with different diameters and the same line spacing have beenprepared.It is found that the easy magnetic axis have been changed from parallel toperpendicular of the array axis with increasing of the diameter,which may be aroseby competition between self demagnetization of the wires and dipolar interactionsbetween the wires.