| Barium hexagonal ferrites are widely used in microwave devices and electromagnetic wave absorbers for their relatively high saturation magnetization, high planar magnetic anisotropy, tunable dielectric properties, and excellent chemical stability. However, pure barium ferrite is unsuitable for microwave absorbing materials becase of their high resonance frequency （42.5GHz for M type barium ferrite） due to their strong c axies anisotropy and low permeability. First, we have synthesised BaFe12O19 samples by coprecipitation, sol-gel auto-combustion method and ethanol assisted method of precipitation. Second, barium ferrites with different doping amount of CoZr (BaFe12-2xCoxZrxO19, x=0, 0.5, x=1.0, x=1.5) were synthesised by coprecipitation method. Finally, BaFe12O19/ZnO composites were fabricated in large scale via high-energy ball milling and subsequently forced hydrolysis of zinc acetate at surface of BaFe12O19 particles in DEG. The phase structures, morphologies, particle size, chemical compositions and electromagnetic absorption properties of these samples have been characterized. we have drawn the following conclusions with Practical Significance:We all know that the formation temperature of barium ferrite is very higher and barium ferrites with pure phase were fabricated with difficulties. Our experiments indicated that droping solution with metal ions into the precipitation agent solution and adsorption BaCO3 on the Fe3O4 particles can lead to barium ferrites with pure phase.Barium ferrites with different doping amount of CoZr show magnetic resonance phenomenon in 1-18GHz frequency range and magnetic loss,BaFe12-2xCoxZrxO19 （x=0.5） got an optimal reflection loss（RL） of -30dB.Forced hydrolysis of zinc acetate at surface of BaFe12O19 particles in Diethylene Glycol （DEG） was firstly used for composite BaFe12O19 and ZnO, and the resulting BaFe12O19/ZnO composite material got an optimal reflection loss（RL） of -37.5dB in the thickness of 6.8mm. |
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