Broad microwave absorption bandwidth achieved by exchange coupling interaction between hard and soft magnetic materials

To gain broad microwave absorption bandwidth over 2-18 GHz, hard/soft magnetic composites Ba(Zr-Ni)(0.6)Fe10.8O19/Fe3O4 have been synthesized in this work. The results show that the raising heat treatment temperature would cause more Fe3O4 particles attach to Ba(Zr-Ni)(0.6)Fe10.8O19 particles, increasing the number of interfaces between Ba(Zr-Ni)(0.6)Fe10.8O19 and Fe3O4 to enhance the hard/soft exchange coupling effect. Finally, the sample heat treated at 400 degrees C possesses the widest magnetic loss range (mu ">0.2) of 12.4 GHz, which contributes to a broad effective absorbing bandwidth of 6.68 GHz at 1.9 mm. The performance is superior than most of the state-of-the-art microwave absorbers.