Morphology and Magnetic Properties of Platelet γ-Fe2O3 Particles
Mikio Kishimoto, Tatsuya Oda, Yusuke Ohara, Ryoichi Miyamoto, Yoshimasa Akashi, Hideto Yanagihara, Nobuhiro Ohkochi, Eiji Kita
The morphology and magnetic properties of platelet α-FeOOH and γ-Fe2O3 particles were studied to use hysteresis-loss heating of ferromagnetic particles in magnetic hyperthermia or thermoablation. The platelet α-FeOOH particles were prepared through the formation of a precipitant followed by the hydrothermal treatment of the precipitant. The shape of the α-FeOOH particles changed from elongated to platelet-like depending on the quantity of ethanolamine in the precipitant. The size of the platelet α-FeOOH particles was reduced from 90–120 to 40–60 nm as the precipitant temperature was lowered in the range from 5 to −3°C. The formation of dimples was observed during the dehydrating process from α-FeOOH to α-Fe2O3, and was confirmed from the increase in the BET surface area of the α-Fe2O3 particles. The particle size and the coercive forces of the platelet γ-Fe2O3 particles were in the range 30–100 nm and 7.6 kA/m (96 Oe) to13.5 kA/m (169 Oe), respectively.