Effect of Iron Content on the Properties of FePt Nanoparticles in Water in Oil Microemulsions

Fe/Pt bimetallic nanoparticles at various molar ratios have been prepared by simultaneous reduction of FeCl2 and H2PtCl6 with hydrazine hydrate in water/Triton X- 100/cyclohexane/pentanol microemulsions at room temperature. The size, structure, composition and the magnetic properties of the resultant nanoparticles were characterized by XRD, EDX, TEM and AGM. XRD patterns indicated the formation of face centered cubic FePt nanoparticles with crystallite size in the range of 4 nm to 8 nm. Higher content of iron resulted in larger FePt nanoparticles. EDX analyses on the samples confirmed the presence of Fe and Pt elements in the particle. The composition for each particle was roughly consistent with the Fe2+ to Pt 4+ ratio of initial solution. TEM micrograph showed homogeneous fine spherical particles. The physical sizes were similar to the crystallite sizes of FePt nanoparticles calculated from XRD. The Fe/Pt molar ratio of 1 to 1 showed optimum magnetic properties with coercivity (Hc) of 68.67 Oe .