Simple synthesis and magnetic properties of Fe3O4/BaSO4 multi-core/shell particles

In this paper, the magnetic properties of Fe3O4 nanoparticles at different temperatures were investigated. It was found that the magnetism of Fe3O4 nanoparticles vanished at 550 °C when exposed in the atmosphere for 2 h. X-ray diffractometer, Fourier transform infrared spectroscope and scanning electron microscope were employed to explain the change of magnetism of Fe3O4 nanoparticles. The route of phase transitions from Fe3O4 to α-Fe2O3 along with the increasing temperature was brought out. In order to maintain the magnetism of Fe3O4 nanoparticles at a higher temperature, a simple method was introduced to deposit BaSO4 shell on the Fe3O4 cores to prepare Fe3O4/BaSO4 multi-core/shell particles. The magnetism of Fe3O4/BaSO4 multi-core/shell particles did not vanish till 750 °C. The change of magnetism of Fe3O4/BaSO4 multi-core/shell particles was proved to be related to the appearance of “holes” on the surfaces of BaSO4 shells.