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

In this work, C@Fe(3)O(4) 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 Fe(3)O(4) nanoparticles were grown on the surface of P(MAA/St) to obtain P(MAA/St)@Fe(3)O(4) microspheres. Using P(MAA/St)@Fe(3)O(4) as the precursors, after vacuum carbonization, C@Fe(3)O(4) 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)@Fe(3)O(4) and C@Fe(3)O(4) increase. The obtained four kinds of C@Fe(3)O(4) 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@Fe(3)O(4) magnetic microspheres. The microwave absorption properties of materials were determined by controlling dielectric loss, magnetic loss and impedance matching. C@Fe(3)O(4) 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@Fe(3)O(4) microspheres were lightweight and efficient microwave absorption materials.