FePt Nanoparticles with a Narrow Composition Distribution Synthesized via Pyrolysis of Iron(III) Ethoxide and Platinum(II) Acetylacetonate

Equiatomic colloidal FePt nanoparticles (NPs) of 4.5-nm mean diameter were chemically synthesized using iron(III) ethoxide and platinum(II) acetylacetonate as precursors. All of the starting materials used in the synthesis were stable in air and had relatively low toxicity. Reaction proceeded without any reducing agent, providing an easy and robust way of synthesis of FePt NPs. FePt NPs were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray fluorescence spectrometry (EDX), and inductively coupled plasma atomic emission spectrometry (ICP-AES). TEM-EDX analysis revealed that FePt NPs contained little oxygen or other impurities. In addition, the atomic composition distribution of each NP was considerably narrow, and seven out of ten NPs contained Fe and Pt atoms necessary to be transformed into the chemically ordered L1 0 crystalline structure. By annealing at 600 °C for 30 min, as-synthesized fcc FePt NPs were transformed into the L1 0 phase and showed coercivity of 11.2 kOe.