Preparation And Characterization Of Magnetic Nanomaterials

Magnetic nanomaterials (MNMs) have been widely used in many fields. It hasbecome a hotspot in the field of MNMs to synthesis morphology-controlled anduniform magnetic nanoparticles (MNPs). Fe3O4NPs, Fe3O4-Ag magnetic compositenanoparticles and FeNdO3MNPs are preparaed in this paper. Details are as follows:(1) Use ferric chloride and ferrous chloride as the raw materials. Prepare Fe3O4MNPs by co-precipitation method. We study the effects of protective agent, the kindsof protective agent and precipitant, reaction temperature on the properties of samples.Get the following conclusions: The products are all superparamagnetic. The saturationmagnetization decreases with reaction temperature increase; When PEG4000(1.5wt%) is used as the protective agent, the diameter of the particle is smaller, moreuniform, and good dispersion. Moreover, there are no obvious lump products.(2) Fe3O4MNPs are prepared by the method above, Ag+is reduced to the silverusing hydrazine hydrate directly at the condition of co-exist of Fe3O4and AgNO3. Agnanoparticles and Fe3O4react with each other to form the composite. Analyze theeffects of the molar ratio of Fe3O4/Ag, reaction time and reaction temperature onpreparation of the composite. The conclusions are as follows: The silver nanoparticlesare first adsorbed on the surface of Fe3O4nanoparticles in the reaction process, andthen react with each to form the composite. The reactions of Ag and Fe3O4requirelonger time completely with the dcrease of molar ratio of Fe3O4/Ag. We can obtainthe samples which there are no obvious agglomeration nanocomposite particles at80°C for8h.(3) FeNdO3MNPs are synthesized via high temperature sintering method, usingferric nitrate and neodymium nitrate as metal precursors and polyvinylpyrrolidone(PVP) as capping agent. The influence of sintering temperature on the relativecrystallinity of products is studied. At last, simultaneous thermal analyzer (TG) andfourier transformation infrared (FT-IR) are used to illustrate the mechanism of theformation of FeNdO3MNPs. The following conclusions are given: The relativecrystallinity increase with the increase of sintering temperature. The prosess ofsynthesizing FeNdO3MNPs is as follows：Fe(NO3)3·9H2O and Nd(NO3)3·6H2O are decomposed to form Fe2O3and Nd2O3, which react with each other at725°C to formFeNdO3MNPs.