Abstract
The present article describes core/shell nanoparticles composed of disordered alloy FePt core and iron-oxide shell with spinel structure for biomedical applications such as magnetic hyperthermia, which requires high ac magnetic susceptibility χ" at around room temperature. The nanoparticles are chemically synthesized by a polyol method in octylether as a solvent using Fe(CO)5 and Pt(acac)2 as precursors, and oleic acid and oleylamine as surfactants. The core/shell nanoparticles are formed under larger amount of Fe(CO)5 and surfactants compared with that for a synthesis of equiatomic FePt nanoparticles. For typical core/shell nanoparticles obtained in this study, the size of FePt core and the thickness of Fe-oxide shell are approximately 9 nm and 1.5 nm, respectively. The shell thickness increases with the increase of a concentration of Fe(CO)5, leading to the increase of the peak value of χ" and the peak temperature in the temperature dependence of χ".
