Preparation Of Different Shapes FePt Magnetic Nanoparticles

The FePt nanoparticles were prepared by direct reduction process. The effect ofCTAB and different types of surfactants on the morphology and properties of FePtnanoparticles were investigated; The FePt nanoparticles were prepared via polyolreduction process. The effect of different types of surfactants on the morphology andproperties of FePt nanoparticles were also investigated. The as-prepared FePtnanoparticles were characterized by Fourier-infrared spectrometer（FT-IR）, X-raypowder diffraction（XRD）, Transmission electron microscopy （TEM） and Vibratingsample magnetometer （VSM）.（1） The FePt nanoparticles were prepared by direct reduction process by using ofFe（acac）₃as Fe resource, H₂PtCI6.6H₂O as Pt resource, sodium borohydride （NaBH₄）as reductant, respectively. The FePt nanoparticles were prepared via polyol-reductionprocess, where ethylene glycol were used as reductant and solvent. The results exhibitthat the FePt nanoparticles were of face-centered-cubic （FCC） structure, and highmono-dispersibility by adding surfactants.（2） The monodisperse FePt nanoparticles were prepared by direct reduction processby using of CTAB as surfactants. with the increase of CTAB concentration, the averagesize decreased at beginning then increased and decreased in the end; The evolution ofthe shapes changing from wormlike to spherical structure with high monodispersibilitywere observed. And the coercivity increased first and then decreased, increased againand then decreased gradually. The higehest coercivity of260kA/m was obtained.（3） PEG-4000, polysorbate-80（nonionic surfactants）; octylamine, oleylamine（cationic surfactants）; oleic acid, SDS, SDBS（anionic surfactants）; oleic acid andoleylamine（complex surfactants） were used as surfactants in the experimental process.The experimental results exhibit that:The monodisperse FePt nanoparticles were prepared via using different types ofsurfactants. Compared with particles synthesized without surfactants,the sizedistributions were very narrow. The FePt nanoparticles with flower-like assembly weresynthesized when chose PEG-4000（nonionic） as the surfactant. FePt nanoparticles withspherical shapes were synthesized when chose polysorbate-80（nonionic） as thesurfactant.When the octylamine, oleylamine （cationic） were used as surfactants, theFePt nanoparticles with irregular and spherical shapes were synthesized. The morphologies of FePt nanoparticles show spherical, spherical and dendritic structurewhen chose oleic acid, SDS, SDBS （anionic） as the surfactants. The FePt nanoparticlesmodified with the complex surfactants oleic acid and oleylamine were mainly sphericalshapes, but contained Cubic structure. VSM indicates that the FePt nanoparticles weresuperparamagnetic when the coercivity approches zero.（4） The results exhibit that the FePt nanoparticles were of superparamagneticbehavior and high mono-dispersibility. The FePt nanoparticles modified with oleic acidand oleylamine were mainly spherical shapes, but contained Cubic structure; whileFePt nanoparticles modified with CTAB were worm-like shapes.