From Core/Shell Structured FePt/Fe₃O₄/MgO to Ferromagnetic FePt Nanoparticles

Abstract

This paper reports an improved synthesis of hard magnetic fct-FePt nanoparticles (NPs) from reductive annealing of fcc-FePt/Fe3O4/MgO NPs followed by MgO removal. The fcc-FePt/Fe3O4 NPs are made by a one-pot reaction of Pt(acac)2 with Fe(CO)5 in the presence of oleic acid and oleylamine and are coated with a layer of MgO via the thermal decomposition of Mg(acac)2. The MgO coating prevents FePt from sintering under high temperature reductive annealing conditions. The fct-FePt NPs obtained from the 650 °C annealing of the fcc-FePt/Fe3O4/MgO NPs show a coercivity value of 2 T at 300 K, suitable for various nanomagnetic applications.