Research On The Microstructure Control And Performance Of Multi-component One-dimensional Magnetic Nanomaterials

One-dimensional magnetic metal nanowires have a wide range of applications because of their high aspect ratio,perpendicular magnetic anisotropy,high coercivity,and easy magnetization.However,it has the characteristics of close packing,and there is a dipole effect between the nanowires,thereby reducing the magnetic properties of the nanowires.The metal nanowires are easily oxidized during the application process,resulting in unstable magnetic properties,which limits their application.To this end,this project starts with the material structure,designs several multi-component nanowire arrays,and adjusts the structure of the multi-component nanowires to study the relationship between the multi-nanowire structure and the magnetic properties,so as to realize the multi-component complex structure.Control the assembly and establish the relationship between the multilayer structure and the magnetic properties.In this work,the Nd/Ni/PA66 three-layer nano-cable array,different sizes of Nd/FM?FM=Fe,Co,Ni?double-layer nanocables,FM-Cu multisection nanowires and NiCo₂O₄ nanowires were assembled using porous anodized aluminum?AAO?template-assisted electrochemical deposition method.Scanning electron microscope?SEM?,transmission electron microscope?TEM?,X-ray diffraction?XRD?and energy dispersive X-ray spectrometer?EDX?were used to perform morphological characterization and chemical composition test on the samples,respectively.A comprehensive physical property measurement system?Quantum Design-PPMS?was used to test the magnetic properties of the samples.An electrochemical workstation?CHI 760E?was used to test the electrochemical performance of the samples.The specific research contents were as follows:?1?The Nd/Ni/PA66 three-layer coaxial nanocable array and the Nd/FM double-layer coaxial nanocable array of different sizes were assembled.The results showed that the three-layer and two-layer coaxial nanocable arrays were successfully assembled with the easy axis of magnetization along the long axis.The magnetic properties of the three-layer nanocable were significantly higher than those of single-component ferromagnetic nanotubes,because polymer nanotubes play a protective role and there was a synergy between rare earth metals and ferromagnetic metals.Hc^//of Nd/FM double-layer coaxial nanocable arrays of different sizes indicated that large-sized nanocables had stronger resistance to demagnetization than small-sized ones.Nd/FM coaxial nanocables are all hard magnetic materials.?2?The FM-Cu multi-section nanowire arrays were assembled,and the results showed that the multi-section nanowire arrays were successfully assembled.The accumulation of magnetic regions resulted in the Hc and Mr/Ms of 5 cycles of nanowires being greater than those of 2 cycles of nanowires.The easy axis of magnetization dominated by the magnetostatic dipole was perpendicular to the long axis,and the multi-section nanowires also had obvious hysteresis and residual magnetism.?3?The Ni Co₂O₄ nanowires were prepared,and the results showed that the polycrystalline NiCo₂O₄ nanowires had finely distributed nanosheets on the top.Ni Co₂O₄ nanowires had obvious shape anisotropy and the easy axis of magnetization was parallel to the long axis.Ni/Co nanowires were oxidized to form NiCo₂O₄nanowires.The participation of oxygen makes the easy axis of magnetization showed greater magnetism,that was,the value of Hc^//increases and Hc^?decreased.NiCo₂O₄electrode material was optimized to show high specific capacitance and enhanced cycling performance...