W Hexagonal Ferrite Preparation And Absorbing Properties

W-type barium hexagonal ferrite presents relativly large saturation magnetization, strong magnetic crystalline anisotropy and good chemical stability,and are widely used in microwave devices and electromagnetic wave absorbers.Focus on the microwave electromagnetic characteristics of W-type hexagonal barium ferrite Ba1Zn2Fe16027,effects of compositions, technology parameters and doping ions on the microwave paraters,and microwave absorbing properties were studied. The W-type hexagonal barium ferrite doped with rare earth ions were especially researched on microstructures and electromagnetic characteristics. Based on microwave loss of the W-type hexagonal barium ferrite, the composites from W-type hexagonal barium ferrite and Fe-based alloy were evaluated electromagnetic properties and microwave absorbing abilitis.A modified sol-gel technology were adopted which enclosed two-step heating process in the calcining stage. After the preheating process, the phase formation temperature of the hexagonal ferrit can be effectively.Substitution of ion doping on microstructures and magnetic properties of the W-type hexagonal barium ferrite were investigated. Firstly, substitution of Zn2+by different amount of Co2+in the position B was explored and it showed that, when the amount of doping Co2+is 0.9, the absorption peak value is-33.6 dB. Furthermore, effects of the doping ions in position A and position B, for example, Ba2+in the position A was substituted by La3+at the amount of bit 0.2 and Zn2+in the position B was substituted by Co2+at the amount of bit 0.9, results show that the W-type hexagonal BaLaCoZn ferrite pesents the peak absorbing value of-39.6 dB.Based on the prepared W-type hexagonal barium ferrite, composties from the ferrite and the iron-based alloy were discussed. When the mass ratio is 2/10, the absorbing peak values of composite materials are-40.6 dB and-51.8 dB respectively for the Za3+doping composite and undoped La3+composite in the layer thickness of 2.2 mm.The absorbing composite materials exhihit high resistivity, good electromagnetic impedance matching and superior high-frequency electromagnetic properties as ferrite, and also large permeability and magnetic loss as the alloy.