Constructing multi-effect synergistic rare-earth doped CoFe2O4/CoFe composites for improved microwave absorption performance

It is an appealing strategy to improving the low reflection loss and narrow microwave absorption band of cobalt ferrite-derived composites by optimizing the various components of the material and building microstructures with complementary properties. In this study, rare-earth doped CoFe2O4/CoFe composites (LCF-2, NCF-2, ECF-2) were synthesized via the sol-gel self-combustion and reduction process, a two-step route. The results show that the effects on the cation vacancies and charge distribution of CoFe2O4 showed differences attributed to the doping of La, Nd, and Eu. While the CoFe introduced by reduction increases the oxygen vacancies and grows on the material surface to form a non-uniform, strongly coupled CoFe2O4–CoFe heterointerface. Benefiting from the multi-effect synergy of rare earth and CoFe on cobalt ferrite, the electromagnetic properties and microwave attenuation of the composites were significantly enhanced. And the potential microwave dissipation mechanism was also explicated. Notably, LCF-2 exhibited superior microwave absorption performance with a minimum reflection loss of −65.2 dB and an effective absorption bandwidth of 5.1 GHz at a thin thickness of 1.6 mm. Our works will provide some reference for the design of efficient and broadband microwave absorbing composites in the future.