Preparation and Microwave Absorption Properties of C@Fe 3 O 4 Magnetic Composite Microspheres.

In this work, C@FeO magnetic microspheres were designed and prepared by a novel strategy, and the microwave absorption properties of the materials were investigated. Four kinds of monodisperse P(MAA/St) microspheres with different carboxyl content were synthesized via facile dispersion polymerization. The FeO nanoparticles were grown on the surface of P(MAA/St) to obtain P(MAA/St)@FeO microspheres. Using P(MAA/St)@FeO as the precursors, after vacuum carbonization, C@FeO were obtained. It was observed that the carboxyl content on the microspheres' surface increased with the increasing of MAA, which made the magnetic content and maximum specific saturation magnetization of P(MAA/St)@FeO and C@FeO increase. The obtained four kinds of C@FeO microspheres had a particle size range of 4-6 μm. The microwave absorption properties indicated that the magnetic content made a difference to the microwave absorption properties of C@FeO magnetic microspheres. The microwave absorption properties of materials were determined by controlling dielectric loss, magnetic loss and impedance matching. C@FeO microspheres exhibited excellent microwave absorption properties. The maximum reflection loss could reach -45.6 dB at 12.8 GHz with 3 mm in thickness. The effective bandwidth was 5.9 GHz with RL < -10 dB. Therefore, C@FeO microspheres were lightweight and efficient microwave absorption materials.