Preparation And Characterization Of Barium Titanate-based And M-type Barium Ferrite Absorbing Materials

In this paper, to measure absorbing properties in the low-frequency(0-6GHZ), bariumtitanate composites modified with magnetic metal、rare earth metal、and conductive polymerwere investigated. And doped M-type barium ferrite were also prepared, its magnetic andabsorbing properties were studied.(1) Barium titanate were prepared by sol-gel mehod, the morphology、particle size andabosording properties characterized shows that the crystal phase of the sample wasapproximately single square shape, uniform size; the absorption peak of barium titanatepowders is3.8dB when the calcination temperature is850℃. But it is also found that theabsorbing properties of composites increased gradually with the ratio of nickel and cobaltreducing. When the ratio of nickel-cobalt is1:4, the barium titanate (850℃) composites hasthe best performance, the absorption capacity is6.8dB.(2) The polypyrrole was synthesized by chemical oxidation and the barium titanatecomposites were prepared by physical composite method. The morphology and absorbingproperties shows that the pure polypyrrole is reticular and the absorption peak of purepolypyrrole is only1.14dB; the composites is uniform spherical and the best absorbingproperties is6.9dB when the mass ratio of1:6;the absorbing properties of composites isenhanced with the increasing of the mass ratio of barium titanate.(3) Barium titanate composite doped with rare earth Nb was prepared by the sol-gelmethod. Absorbing performance tests show that rare earth Nb-doped can greatly increase thedielectric loss materials, broadening the absorption band. When nBaTiO3: nNbis1:0.008, themaximum absorption peak of is29.6dB, the absorption bandwidth of is1.6GHz.(4) The rare earth-doped were prepared by the self-propagating combustion method, the wave-absorbing analysis showed that: rare earth-doped BaFe12O19absorb better than purebarium ferrite, and absorbing properties of Ce-doped is optimal (-4.3dB). Meanwhile Ce-Co-doped BaFe12O19were prepared, the and calcination temperature on the magnetic propertiesare affected. When the calcination temperature is850℃, the coercive force decreasesobviously with the increase of amount of doping. And for Ba (CeCo)0.4Fe11.2O19sample,the morphology analysis showed it is acicular structure when the calcination temperature is850℃; it is Sheet structure when1000℃; it is grainy when1100℃. The sheet structure haslarge specific surface area, electromagnetic wave absorption capacity may be strongest.(5) Ce-Co Co-doped BaFe12O19absorb better than pure barium ferrite (-1.0dB). Whenthe The amount of doping is0.4and1.6, the minimum-return loss are-15dB, and theeffective bandwidth is more than1.5GHz. The position of minimum reflection losses occurbetween both4.5GHz and5GHzwith the change of the amount of doping.