Preparation And Physical Properties Of The Ferrite Powders And Thin Films

Sinice Ferrite is as one of the most important modern functional materials, it’s unique properties has attracted a great deal of research in application. Many literatures reported that when material size reduced to nanoscale, it will produce some special perforrmance that make it have great potential ability in application fields. The application of MnFe2O4 magnetic nanoparticles in medical health care, stealth technology, magnetic resonance imaging(MRI), lithium-ion batteries, magnetic fluids, photocatalysis, data storage etc require its’ uniformity monodisperse with nanoscale narrow size. Many experimental methods are reported about synthesizing small size, uniformly monodisperse nanoparticles, such as sol gel, thermal decomposition, the polyol method, etc. However, these methods are high cost, dissipating, process more complex.Having the unique electromagnetic properties of high Curie temperature, half Metallic properties, 100% spin polarization of Fe3O4, enabling it have huge potential in application fields such as battery electrodes, absorbing material, spin-electronics etc, has attracted peoples’ strong interest of preparing Fe3O4 film. Various experiment methods has been reported about preparation of Fe3O4 film like magnetron sputtering, laser molecular beam epitaxy, metal chemical precipitation and so on. However, these methods require expensive experimental apparatus, process complex, high cost, unsuitable for large scale production.The innovation point of this paper is syntheisizing uniformly monodispersed MnFe2O4 magnetic nanoparticles via polyol mixed hydrothermal method, preparing Fe3O4 thin film by using sol gel method, ordinary simple hydrothermal growth of Fe3O4 thin on pure iron foil,which were in low cost and dissipating, technically simple and low equipment requirement. In addition, to date preparation of Fe3O4 film on iron substrate has not reported. This paper consists of the following four parts:In first part, MnFe2O4 nanoparticles were synthesized via hydrothermal method with changing concentration of NaOH, and the influence of concentration of NaOH on the particle size and phase were studied. The experimental results show that When NaOH concentration up to 29.62 mol/L, it produce pure phased, the smallest sized MnFe2O4 magnetic nanoparticles.In second part, under condition of concentration of NaOH ware 29.62 mol/L, small sized(less than 10 nm), uniformly monodispersed MnFe2O4 magnetic nanoparticles were controllably prepared via polyol mixed hydrothermal method with simple craft and low coast. Experimental results show that TREG has dispersion effect on MnFe2O4 magnetic nanoparticles. However, when the reaction temperature more than 24 h, the size of the nanoparticles is still tend to aggregation and big size. Samples of property tests show that when MnFe2O4 nanoparticles size less than 10 nm, shows the unique performance.In third part,Fe3O4 magnetic thin films were prepared on single crystal silicon, glass, ITO glass, respectively, via a simple sol gel method, and substrate effect on the experimental results are discussed.In fourth part, octahedron Fe3O4 magnetic thin film were grown on pure iron foil by using ordinary simple hydrothermal method, and the effects of reaction time on surface properties of thin film and thickness ware discussed. When the was 24 h,the surface of as prepared this film was smooth, pore free, its thickness is 20.7 ?m, saturation magnetization is 407 emu/cm3 and coercivity with 10 Oe, showed soft magnetic properties.