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

Highlights: • Plate-like BaFe₁₂O₁₉@Fe₃O₄ composite was prepared by the hydrothermal method. • An optimal R_L as low as −33.6 dB can be achieved with the thickness of 2.5 mm. • The enhanced properties are ultimately due to the exchange coupling effect. 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).