Abstract: Nanocrystalline composite oxide BaFe₁₂O₁₉ was synthesized via a citrate method. The composite was characterized by means of X-ray powder diffraction and infrared spectral analysis. Nanocrystalline composite oxide BaFe₁₂O₁₉ and the traditional micro wave absorbing mat erial, iron powder were dispersed into the macromolecule polymer uniformly and respectively. Microwave-absorbing coatings with a two-layer structure were obt ained by smearing the mixture of the composite dispersed in the macromolecule polymer, and the mixture of the iron powder dispersed in the macromolecule polymer alternatively on the iron plate until the total thickness being only 1 mm, in this case, a big reflection loss over broadband is realizable. The possible microwave absorptive mechanisms of nanocrystalline material are also discussed on the basis of the experiments.

Key words: microwave absorption, composite material, barium ferrite, nanocrystal