Synthesis and characterization of L10 FePt nanoparticles from Pt-Fe3O4 core-shell nanoparticles

Pt/Fe3O4 core-shell nanoparticles have been prepared by a modified polyol method. Pt nanoparticles were first prepared via the reduction of Pt(acac)2 by polyethylene glycol-200 (PEG-200), and layers of iron oxide were subsequently deposited on the surface of Pt nanoparticles by the thermal decomposition of Fe(acac)3. The nanoparticles were characterized by XRD and HR-TEM. The as-prepared Pt/Fe3O4 nanoparticles have a chemically disordered FCC structure and transformed into chemically ordered fct structure after annealing in reducing atmosphere (4% H2, 96% Ar) at 700 °C. The ordered fct FePt phase has high magnetic anisotropy with coercivity reaching 7.5 kOe at room temperature and 9.3 kOe at 10 K.