The Effect of Alkaline Media and Temperature on ‎the Structure and Magnetic Properties of Magnetic ‎Nanoparticles Modified with PEG

Magnetic nanoparticles were synthesized and coated by the situ-coprecipitation method with FeCl۳.۶H۲O and FeCl۲.۴H۲O precursors in the presence of NH۴OH (or NaOH) reduction and PEG coated agent. Preparation of modified magnetic nanoparticles were performed at two different temperatures under the influence of different alkaline media. The effect of strength of alkaline media and reaction temperature of the magnetic properties (Magnetic saturation, Magnetic remanent, coercive force (of modified MNPs were investigated. To study structure, morphology, optic and magnetic properties MNPs were characterized by XRD, FTIR, TEM and VSM analyzes.The results showed that modified magnetic nanoparticles have superparamagnetic properties and have high magnetic saturation and small coercive force, so the magnetic properties of the modified MNPs are depended to the strength of the alkaline remanent directly. The saturation magnetization of the synthesized sample in NH۴OH and NaOH at ۸۰° C was determined as ۶۰.۹۴ and ۴۹.۳۹ emu/g, respectively. Also increasing temperature, improves magnetic properties coated MNPs) at temperatures below the blocking temperature. (The results of the XRD analysis showed that the structure of the modified magnetic nanoparticles is inverted spinel and the size of the nanoparticles synthesized in the ammonia media is smaller than the other media. The results of FTIR optical analysis revealed that the peaks at ~۵۷۰ and ~۴۴۰ cm^(-۱) indicates the bond Fe-O. TEM analysis indicated that the shape of the MNPs is pseudo-spherical. VSM analysis indicated that the magnetic nanoparticles synthesized in stronger alkaline media (ammonia) and high temperature showed better magnetic behavior by higher magnetic properties.

کلیدواژه ها:

Magnetic nanoparticles ، Superparamagnetic ، Magnetic properties ، Magnetic Saturation