Researches On W-type Ferrites Composite Absorptive Materials

W-barium ferrites of Hexagonal ferrite was chosen in this paper. And a series of barium ferrites particles was prepared by co-precipitation-fused-salt method, Sol-Gel method and surface coated method. DTA-TG, XRD and SEM were employed, to investigate materials'structure and micro-morphology under different processes. Further researches were focused on the improvement of ion-doped ferrites and composite ferrites with other absorbents.Experiments results show that:(1) The W-type barium ferrite nano-particles can be obtained while the precursor prepared by co-precipitation-fused-salt method is sintered at 1050℃; (2) Cenosphere and ferrite was in 1:1 wt% proportion in the preparation of precursor, well-coated ferrite can be obtained on condition that the solution was acidic. Electro-magnetic parameters and reflectivity test results shows that, compared with pure W-type ferrite, ferrites coated by cenosphere have better absorptive ability and wider absorptive bandwidth. (3) When Fe³⁺ is replaced by Al³⁺, the absorbing properties were weakening; however, the absorbing band is changed. Electrical loss and bandwidth can be increased by the doping of ZnO; (4) when it refers to electromagnetic parameters, pure W-type barium ferrites has higher dielectric loss than M-type barium ferrites and both have different characteristic absorption peaks. When they were mixed and synthesized into composite absorptive materials, its performance is better that either of them.