Synthesis and electromagnetic wave absorption properties of Gd‐Co ferrite@carbon core–shell structure composites

Abstract Developing high‐performance electromagnetic absorbing materials remains a challenge. In this work, Gd‐Co ferrite@carbon core–shell structure composites were synthesized by a two‐step hydrothermal method. The effects of rare earth Gd doping amount on the microstructure and electromagnetic wave absorption properties of cobalt ferrite@carbon composites were mainly studied. The results show that an appropriate amount of Gd doping can refine the crystal grain size of cobalt ferrite@carbon composites. However, when the doping amount of Gd exceeds the solid solubility threshold, the secondary phase GdFeO 3 will be generated and the grain size will increase. When the doping amount of Gd is x = 0.04, the reflection loss (RL) of the CoFe 1.96 Gd 0.04 O 4 @C composites reaches the minimum value of − 9.26 dB at the absorption layer thickness of 2.0 mm and a frequency of 13.67 GHz, and the effective absorption band (EAB) is 5.01 GHz (10.95–15.96 GHz). Compared with the CoFe 2 O 4 @C composites, the RL of the CoFe 1.96 Gd 0.04 O 4 @C composites is increased by 79.35%, and the EAB is broadened by 3.51%. Gd ions enhance the dielectric loss through the grain size effect, and the increase of magnetocrystalline anisotropy enhances the magnetic loss. The CoFe 1.96 Gd 0.04 O 4 @C composites have excellent impedance matching, which relies on the strong magnetic loss of ferrite, the interface polarization, and dipole polarization formed by the carbon shell to attenuate electromagnetic waves.