Balance dielectric and magnetic losses to enhance the microwave absorption performance of CaFe0.5Mn0.5O3-δ@Co3O4@Fe3O4

Abstract

Composite materials can combine the advantages of different materials in terms of dielectric loss and magnetic loss to achieve a common balance between the two. As microwave-absorbing materials, composite materials have become increasingly important. Herein, particles of CaFe_0.5Mn_0.5O_3-δ were prepared by a sol-gel method. Then, CaFe_0.5Mn_0.5O_3-δ@Co₃O₄ composites were prepared by a chemical coprecipitation method and annealed. Finally, CaFe_0.5Mn_0.5O_3-δ@Co₃O₄@Fe₃O₄ composites were prepared by another chemical coprecipitation method. Next, the phase composition, microstructure and morphology, magnetic properties and electromagnetic parameters of the three materials were characterized. The successful synthesis of CaFe_0.5Mn_0.5O_3-δ@Co₃O₄@Fe₃O₄ composites with three layers was realized. The CaFe_0.5Mn_0.5O_3-δ@Co₃O₄ encapsulated in the inner layer was found to have a large dielectric loss capacity. The outermost layer of Fe₃O₄ was found to compensate for the weakness of CaFe_0.5Mn_0.5O_3-δ@Co₃O₄ with magnetic loss. Finally, due to the effects of the dielectric loss and magnetic loss, the CaFe_0.5Mn_0.5O_3-δ@Co₃O₄@Fe₃O₄ composite exhibited excellent microwave absorbing performance. So far, the use of a two-step chemical co-precipitation method to compound Co₃O₄ and Fe₃O₄ with another material at the same time has not been reported. The sample had a maximum reflection loss of -46.58 dB at 9.04 GHz, and an effective absorption bandwidth (EAB) of 4.1 GHz. This research provides a new idea for the composite microwave absorbing materials.