Synthesis of fine magnetite powder using reverse coprecipitation method and its heating properties by applying AC magnetic field

Abstract Nano-sized FeFe 2 O 4 ferrite powder for local thermal coagulation therapy was synthesized by a reverse coprecipitation method. The crystal diameter for the samples from the reverse coprecipitation method was smaller than that from a normal coprecipitation method. The crystal diameter increased with an increase in the synthesized temperature for both methods. The maximum increasing temperature under the AC magnetic field was at around a 12 nm crystal diameter. The FeFe 2 O 4 powder was oxidized to Fe 2 O 3 by calcination at 600 °C in ambient air. The heating ability almost depended on the hysteresis loss value. Although the increased temperature under the AC magnetic field for the fresh FeFe 2 O 4 sample was very close to that for the commercialized MgFe 2 O 4 powder, it was gradually decreased for FeFe 2 O 4 with time in ambient air.