Study On Doping In W-type Ferrite Absorbing Materials And Their Electromagnetic Properties

The original intention research of absorbing materials was to improve theweapons of survival and combat effectiveness, but with modern electronic information technology, electromagnetic pollution of space, the electromagnetic radiation on the human body has a great degree of damage. Therefore, the application of absorbing materials used not only the military stealth, but also used inmany civilian areas, such as television broadcasting, communications and navigation system electromagnetic interference.The W-type ferrite has excellent absorbing properties derived from the bestabsorption properties sheet structure, the higher the magnetic anisotropy andthe natural resonant frequency of equivalent field. However, it can not meet the requirements of new generation of radar stealth which is strong absorption, frequency bandwidth, light weight and thin thickness.The W-type barium ferrite with hexagonal lamellar structure, is prepared by chemical coprecipitation, which size is between4-6μm. We study the A-siteelements (Sr and REE: La, Nd, Sm and Dy) doped W-type barium ferrite in this paper. Research shows: The doping of A-site does not change the structureof W-type barium ferrite; The doping of A-site increase the domain wall magnetic loss by increasing the resistance, it increase the dielectric loss by increasing the concentration of Fe2+; The doping of A-site reduce thickness of the impedance matching material; Thd La doping works is the best; The material havethe better absorbing when the amount of doping La is0.6; the absorption peak can reach-39.61dB at the4.6mm when the amount of La is0.3.We study the B-site elements (Zn, Cu, Mn and Ni) doped W-type bariumferrite in this paper. Research shows: The doping of B-site does not change the structure of W-type barium ferrite; The doping of B-site increase magnetic loss mainly through increased relaxation losses, had little effect of the dielectricloss; The doping of B-site can improve the bandwidth of effectively absorbingand the absorbing peak; Thd Zn doping works is the best; the absorption peakscan reach-57.03dB at the5.0mm when the amount of Zn is0.9. A new composite absorbing materials is prepared, which is W-type lanthanum barium ferrite/carbon nanotube. Research show that carbon nanotube composite W-type lanthanum barium ferrite can significantly improve the W-type barium ferrite absorbing properties, the optimum doping ratio of carbon nanotubesis2.5%.