Chemically synthesized FePt nanoparticles with controlled particle size, shape and composition.

Monodisperse Fe-Pt nanoparticles have been prepared by thermal decomposition of iron pentacarbonyl [Fe(CO)5] and reduction of platinum acetylacetonate [Pt(acac)2] with dibenzyl ether in the presence of oleic acid and oleyl amine. The particle composition was adjusted by changing the Fe(CO)5/Pt(acac)2 molar ratio while fixing the Pt(acac)2 amount. The size of FePt nanoparticles was tuned by controlling the injection temperature of the iron precursor. The low injection temperature of precursors and the usage of surfactants as a reaction solvent, together with a slow heating to a low refluxing temperature, were found to be the key parameters for the formation of cubic nanoparticles. Nanorods were formed by simply adjusting the injection time of the surfactants. The as-made nanoparticles had a low coercivity, which was increased to 7 kOe when annealed at 800 degrees C for 1 h.