Synthesis and magnetic properties of platelet γ-Fe2O3 particles for medical applications using hysteresis-loss heating

Abstract

Platelet γ-Fe2O3 particles of particle size less than 100nm were prepared for medical applications that use the hysteresis-loss heating of ferromagnetic particles. The γ-Fe2O3 particles were obtained through the dehydration, reduction, and oxidation of platelet α-FeOOH particles, which were synthesized by the precipitation of ferric ions in an alkaline solution containing ethanolamine, and the crystals grown using a hydrothermal treatment. The γ-Fe2O3 particles contained dimples formed by the dehydration of α-FeOOH particles. The coercive force and the saturation magnetization of the γ-Fe2O3 particles were in the ranges 11.9 to 12.7kA/m (150 to 160Oe), and 70 to 72Am2/kg (70 to 72emu/g), respectively. The specific loss power of the γ-Fe2O3 particles, estimated from their temperature-raising property measured under a peak magnetic field of 50.9kA/m (640Oe) and at a frequency of 117kHz, was 590W/g. This value is higher than that of spherical cobalt-containing iron oxide particles having equivalent coercive force and saturation magnetization, reflecting the larger area of the minor hysteresis loop measured under a peak magnetic field of 50.9kA/m (640Oe).