Effect Of Organic Surfactant On The Magnetic Property Of FePt Nanoparticles

In this thesis，FePt nanoparticles were prepared via chemical reduction process. Inthe process of preparation to join different organic surfactant，with the addition ofdifferent molar ratio of surfactant to precursors. The effect of organic surfactant onmagnetic properties of FePt nanoparticles were investigated. And their crystallinestructure，particle size，morphology and magnetic properties were characterized byX-ray diffraction， Transmission electron microscope， FTIR Spectrometer andVibrating Sample Magnetometer. The specific content was given as follows:（1） FePt nanoparticles were prepared by chemical reduction process, whereFe（acac）₃, H₂PtCl₆·6H₂O and NaBH₄were used as Fe³⁺sources, Pt⁴⁺sources andreductant, respectively. The as-prepared FePt nanoparticles were characterized byX-ray powder diffraction （XRD）, Transmission electronmicroscopy （TEM）, FTIRSpectrometer and Vibrating Sample Magnetometer （VSM）. The results show thatas-synthesized FePt nanoparticles were of face-centered-cubic（fcc）structure anddisplaying superparamagnetic as the coercivity of it was zero, the surfactant improvedthe dispersity of as-synthesized nanoparticle system.（2） FePt nanoparticles were prepared via chemical reduction process by using ofPVP as surfactants, the result give size of around1.9-2.5nm and morphology ofspherical nanoparticles. The effect of PVP on the magnetic property of FePtNanoparticles was researched. The results show that FePt nanoparticle was annealed at600℃for30min in argon atmosphere（Ar）, with the increase of PVP concentration, thecoercivity increased at beginning then decreased. When the as-prepared FePtnanoparticles with PVP:Fe（acac）₃=7:1, the higehest coercivity of434.49kA·m^-1wasobtained.（3） FePt nanoparticles were prepared via chemical reduction process by using ofPEG as surfactants, the result give size of around3.8-4.3nm and morphology offlower-like assembly nanoparticles. The effect of PEG on the magnetic property ofFePt Nanoparticles was studied. The results show that FePt nanoparticle was annealedat600℃for30min in argon atmosphere（Ar）, with the increase of PEG concentration,the coercivity increased at beginning then decreased. When the as-prepared FePtnanoparticles with PEG:Fe（acac）₃=9:1, the higehest coercivity of155.71kA·m^-1wasobtained.（4） FePt nanoparticles were prepared by chemical reduction process by using ofsds as surfactants, the result give size of around3.6-4.1nm, monodisperse andmorphology of spherical nanoparticles. The effect of sds on the magnetic property of FePt Nanoparticles was researched. The results show that FePt nanoparticle wasannealed at600℃for30min in argon atmosphere（Ar）, with the increase of sdsconcentration, the coercivity increased at beginning then decreased. When theas-prepared FePt nanoparticles with sds:Fe（acac）₃=9:1, the higehest coercivity of20.56kA·m^-1was obtained.