Growth of Fe3O4 Particles and Their Magnetic Properties

Fe3O4 particles, prepared by a sol-gel method, were examined for their structural characteristic, particle shapes and sizes, and their magnetic properties. Two different chemical compositions (using a mol rate Fe2+/Fe3+ = 1/2 and only Fe2+) and 2-methoxyethanol were used for making proper solutions. And the solutions were refluxed and dry in a dry oven and the samples were fired at 200 similar to 600 degrees C in the N-2 atmosphere. The formation of single-phased spinel ferrite powders was identified with the X-ray diffraction measurement as they were fired at above 250 degrees C. The result of scanning electron microscopy measurement showed the increase of annealing temperature yielded the particle size increased. The magnetic transition was observed using the Mossbaur spectroscopy measurement. As the ferrite, prepared with the chemical composition (Fe2+/Fe3+ = 1/2), was fired at 250 degrees C, 78% of the ferrite had a ferrimagnetic property and 22 % of the ferrite was non-magnetic. In case of preparing the sample with only Fe2+ and annealed at 200 degrees C, it had a single phased spinel structure but its particle size was too small to be ferrimagnetic. The annealing temperature above 250 degrees C made powders a spinel structure regardless of the preparation method. They had a typical soft magnetic property and their saturation magnetization and coercivity became larger as the annealing temperature increased.