Hydrothermal Preparation Of Copper-based Magnetic Nanostructure And The Study Of Its Magnetic Behavior

Metals and alloys have been studied extensively for their practical important applications in the fields of construction, decoration, nation-defending, magnetic storage and so on. In addition, The demand of the preparation of new materials has being increased urgently, with the increase of technology standard and increasing social need, Hydrothermal technique, one of the most important tools for advanced materials processing, plays an important role in the preparation of electronics, optoelectronics, catalysis, ceramics, magnetic data storage, biomedical, biophotonics, etc, due to its predominance in materials preparation. Hydrothermal technique not only can get monodispersed and highly homogeneous nanoparticles, but also acts as one of the most attractive techniques for doping and nanocomposite materials preparation. In addition, some traditional synthesis parameters including temperature, time and pressure cannot meet the demand of current science and technology. Magnetic field, a common energy supply system, is often used for the measuring of materials magnetic performance. While in this paper, it will be tried to control material structure and properties, which is believed to influence the crystal growth of magnetic nanoparticles and microstructure effectively and finally, we could obtain the materials with desired properties. The details will be summarized as follows:1. In the first part, We discussed the growth mechanism of Cu-Ni alloy nano-materials using the hydrothermal method under an external magnetic field and compared the samples prepared with and without magnetic field. It was found that the external magnetic field not only affect the dynamic behavior during the hydrothermal preparation, but also change the microstructure, composition of the product and the self-assembly behavior. In this chapter, we will mainly discuss the roles and the influences of the magnetic field in the synthesis and on the growth of nanoparticles in terms of nucleus formation, crystal growth2. In the second part, we discussed the hydrothermal preparation of copper ferrite powders, study the influences of coordinating agents on the formation of copper ferrites, clarify the standards for the synthesis of copper ferrites and investigate the influences of the applied magnetic field on the copper ferrite's magnetic properties. Ferrite is widely used as non-metallic magnetic materials in the area of high-frequency and light current. The poor magnetic energy stored per unit volume and low magnetic saturation magnetization limit the use in the domain of the low-frequency electric and high-power fields. This paper will study the affection of magnetic field in the preparation of copper ferrite and explore ways to improve the magnetic properties. The conclusion of the experiment of iron oxide magnetic materials play a fundamental significance on the study of improving magnetic property of ferrite.3. One-dimensional (ID) chainlike Ni0.33Co0.67 alloy nanostructures and wirelikeNi0.67Co0.33 alloy nanostructureswere solvothermally prepared at 180℃under an external magnetic field. The morphologiesand structures of these samples were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM).Magnetic measurement results reveal that both of these two nanostructures possess higher saturation magnetization Ms, remnant magnetization Mr,coercivity He and reduced magnetization Mr/Ms, compared with those of randomly distributed alloy particles prepared in the absence of an external magnetic field. A possible growth mechanism was proposed to account for the microscopic assembly behaviors inducedby the applied magnetic field.4. In part 4, we explored a way of preparing opper oxide nanostructures arrasy using solvenst water, ethanol and copper foil in the hydrothermal system. The different properties of copper oxide prepared in two solutions were discussed by comparing the morphologieds of the two samples. And a specified affordable way was indicated for the preparation of other metal-oxide semiconductor.