Controllable Preparation and Microwave Absorbing Properties of FeBP@SiO₂ Core-Shell Nanocomposites

Core-shell FeBP@SiO2 nanoparticles were prepared by a facile method. This method combines chemical reduction and sol-gel to realize the controllable core-shell structure of composite particles. By changing the thickness of SiO2 shell, the effect of shell thickness on microwave absorption performance was studied, and the microwave absorption mechanism was analyzed. Results show that with increasing the SiO2 shell thickness, the microwave absorption capacity of the particles is increased firstly and then decreased. When the thickness of the SiO2 shell is 38 nm, the FeBP@SiO2 sample has the strongest microwave absorption performance, and the sample with the absorption coating thickness of 2.19 mm obtains better absorption performance (-52.66 dB). This enhanced microwave absorption performance is mainly attributed to the new magnetic-dielectric interface, which improves the impedance matching and dielectric loss of the material. By designing the core-shell structure of the composite particles, the performance regulation of the composite absorber can be achieved. Therefore, this work provides an important reference for the design of the next generation composite microwave absorbing materials.