Preparation Of Ferrite Magnetic Nano-micro Materials In Ionic Liquid Medium

Ferrite nanomaterials have been widely applied in biotechnology and electromagnetictechnology fields due to their interesting magnetic and environment-friendly properties. Inorder to investigate the relationship between structure and property of ferrites and furtherdevelop their applications, the research of controllable preparation of ferrites is veryimportant. Herein, microemulsion and vapor-diffusion methods were used to prepare theferrite magnetic nano-micro materials in ionic liquid medium, which possesses excellentproperties such as low volatility, thermal stability and good solubility.Firstly, core-shell nickel ferrite microspheres were prepared by a microemulsionmethod. The microemulsion was constituted of ionic liquid, benzene and Triton X-100.FeCl3·9H2O and NiCl2·9H2O were used as starting materials and urea as a precipitant. Themorphologies, structures and magnetic properties were characterized by field emissionscanning electron microscopy (SEM), transmission electron microscopy (TEM), X-raydiffraction (XRD), thermogravimetry (TG), vibrating sample magnetometer (VSM). Theinfluences of reaction temperatures, reaction times, mass ratios of ionic liquid to oil phase,kinds of anionic groups of ionic liquid, kinds of organic solvent and reaction conditions onthe structures, morphologies and magnetic properties of the products were investigated.Results showed that uniform core-shell nickel ferrite microspheres with a diameter of5μmwere prepared at160oC with24h, and the mass contents of1-butyl-3-methylimidazoliumbromide, benzene and Triton X-100were10%,20%and70%. And the saturationmagnetization of the products was15.804emu/g.Secondly, the nanoporous nickel ferrite microspheres were prepared by a vapordiffusion method in the mixed solution of1-butyl-3-methylimidazolium bromide([BMIm]Br), polyvinylpyrrolidone (PVP), ethanol and cyclohexane. The urea was used asprecipitant. The effects of rection temperature, the PVP concentration and the volumeration of ethanol to cyclohexane on products were investigated. The morphologies andstructures of the products were characterized using SEM, TEM and XRD. Results showedthat the nanoporous nickel ferrite microspheres with a diameter of600nm were prepared at160oC with PVP of0.10g/ml, and the volume ratio of ethanol to cyclohexane was3:1.Finally, nanoporous nickel ferrite microspheres were synthesized by a vapor-diffusionprocess in ionic liquid with PVP as template, and urea as a precipitant. The morphologies,structures and magnetic properties of as-prepared materials were characterized using SEM, TEM, XRD and VSM. The influences of the chain length and the kinds of anionic groupsof ionic liquid on the structures, morphologies and magnetic properties of the products werestudied. Results showed that uniform nanoporous nickel ferrite microspheres with diameterof about300nm were prepared in ionic liquid of [BMIm]Br, and the saturationmagnetization of the products was7.664emu/g.