Synthesis and microwave absorption properties of plate-like BaFe12O19@Fe3O4 core-shell composite

A novel plate-like BaFe12O19@Fe3O4 core-shell composite was successfully synthesized by a hydrothermal method. The phase structure and morphology of as-prepared composite was characterized by XRD, SEM and TEM. The results show that uniform Fe3O4 microspheres with a diameter of about 10 nm were generated as the shell of plate-like BaFe12O19 grains. The static magnetic properties and electromagnetic parameters in the microwave range were measured using a vibrating sample magnetometer and a vector network analyzer, respectively. The obtained BaFe12O19@Fe3O4 composite exhibits a saturation magnetization of 43 emu/g and a coercivity of 224 Oe at room temperature. A minimum reflection loss of −33.6 dB was observed at 11.6 GHz with a thickness of 2.5 mm in the frequency range of 2-18 GHz, indicating the excellent microwave absorption performances of the novel composite. This improvement in microwave absorption can mainly be attributed to the enhanced magnetic properties due to the exchange coupling effect between the hard magnetic phase (BaFe12O19) and the soft magnetic phase (Fe3O4).