Preparation And Study Of Nanoporous Templates And One-dimensional Magnetic Nanomaterials

Over the past decade, one-dimensional nanomaterials prepared by template method has attracted a huge scientific interst, especially in basic research field of magnetic materials. Highly ordered and adjustable templates brings great convenience and opportunities to the basic research of magnetic nanowires(nanotubes) and the application in magnetic storage, magnetic sensors, microwave devices, etc. The main works of this paper can be divided into two part: the preparation and study of the templates and one-dimensional magnetic materials – nanowires or nanotubes.In this paper, we have been developed kinds of anodic alμminμm oxide(AAO) template with different anodizing process, and explored the preparation method of the attached anodic alμmina template on silicon and porous silicon template. The AAO template with pore distance of 100 nm and 125 nm have been fabricated under a voltage of 40 V and 50 V in the oxalic solution, respectively. What’s more, we found that an appropriate increase of the oxidation temperature could accelerate the growth rate of oxide film in the case where AAO templates remain highly ordered. The highly ordered AAO template with both sides consistent was prepared by gradually increase of the electrolyte concentration and two-step anodization process, which offer a new way to improve the coherence of the hard-anodization AAO, and it is promising applicate in other hard-anodization systems. Combined with pore enlarge process, the pore diameter of these AAO templates range from 60 nm to 200 nm with the pore distance of 265 nm. In addition, the attached anodic alμminμm oxide template have successfully prepared by transferred the ultrathin AAO template on silicon substrate or flexible PE substrate under the protection from polymer film. Finally, the porous silicon template was tried fabricate by combine with the self-assembly block copolymers film and metal-assisted chemical etching technique. In a word, the homemade templates offered various chooses for fabricate one-dimensional magnetic materials.Based on homemade AAO templates, the Fe nanowire arrays with different pore distance and amorphous Fe-P alloy nanowires(nanotubes) have been fabricated by electrodepositon, and the influence of pore distance, the preparation process conditions and the thermal annealing on the structure and properties of nanowires(nanotubes) were to be studied. The results indicated that because of the magnetic coupling between the nanowires could reduce the magnetic anisotropy of magnetic nanowire arrays, the coercivity and remanence of Fe nanowire arrays in easy axis was decreased with pore distance decreased. What’s more, the high frequency electromagnetism performance of the Fe nanowires arrays was studied by Coaxial air-line method which provide an new way to measure the high frequency property of magnetic nanowire arrays, and the Fe nanowire arrays was promising to apply in novel magnetic microwave devices. In our works, the amorphous Fe-P alloy nanowires(nanotubes) arrays with high P content were prepared by control the concentration of glycine and sodiμm hypophosphite and deposition potential. The magnetocrystalline anisotropy of the amorphous Fe-P alloy nanowires(nanotubes) arrays enhanced after the Fe and Fe3 P phase crystallized after thermal annealing. Thus the coercivity and remanence ratio of Fe-P nanowires array was improved, while the whole magnetic anisotropy became weaken. Due to the different magnetization mechanism from nanowires, only the coercive of the Fe-P nanotues increase obviously while the ratio of the remanence and the whole magnetic anisotropy show litte changes, when the Fe-P nanotubes magnetocrystalline anisotropy improved after thermal annealing.