Preparation And Microwave Absorption Property Of BaFe_12-xTi_xO₁₉/Carbonyl Iron Powder Nanocomposites

Microwave absorbing materials were widely used in the electromagnetic shielding,aerospace and stealth technology and other fields preventing electromagnetic radiation,radar stealth materials.Absorbing materials require strong absorption,wide band and low-density.Doped and composite materials are the main research direction of microwave absorbing materials.Barium ferrite(BaFe₁₂O₁₉)has the property of high Curie temperature,relatively large magnetization,fairly large magnetocrystalline anisotropy and excellent chemical stability and corrosion resistivity.Microwave absorption of barium ferrite primarily bases on magnetic resonance phenomenon and it has the disadvantage of narrow wave-absorbing band and small dielectric constant.It maybe get a better microwave absorption property of barium ferrite by titanium doping of transition element.Carbonyl iron powder?CIP?has a good microwave absorption property in the frequency of 8-12 GHz.But it has the disadvantage of large density and poor chemical instability.Usually we composite the CIP with the other materials to enhance its performance of wave absorption.In this experiments,we prepared Ti-doped barium ferrite nanoparticles by sol-gel method,and then prepared Ti-doped barium ferrite/CIP nanocomposites by physical blending method.Trying to prepare the nano fiber of barium ferrite by the electrostatic spinning method.Analysing the nanocomposites by XRD,FTIR,SEM and vector network analyzer.The main conclusion:1.The crystal of Ti-doped barium ferrite prepared by sol-gel method is good calcining at 1100 ?.A small amount of titanium doping does not affect the crystallization of barium ferrite,but too much will cause the system appear ?-Fe₂O₃ impurities.2.The absorbing performance of Ti-doped barium ferrite is improved.BaFe_11.4Ti_0.6O₁₉ has the largest microwave absorption of-16.89 dB at 6.5GHz with the coating thickness of4.5mm.3.Analysing the electromagnetic parameters of the nanocomposites of BaFe_11.4Ti_0.6O₁₉ with CIP of different quality ratio.It can be seen that the real part of dielectric constant gets bigger and the imaginary part has no evident changes by the quality increasing of CIP.The real component of permeability shows a trend of increasing in general by the quality increasing of CIP.And the imaginary part of the permeability increased which can improve the ability of magnetic energy loss of the nanocomposites.It shows that the absorbing performance of the composites enhances mainly caused by magnetic loss changing.4.Analysing the electromagnetic parameters of the nanocomposites of different titanium doping amount of barium ferrite with CIP quality ratio of 1:0.3.It can be seen that in the case of BaFe_12-xTi_xO₁₉/ CIP nanocomposites in the ratio of 1:0.3,the real part of dielectric constantgets bigger by the titanium mixed.And the imaginary part of dielectric constant shows a trend of increasing which can improve the ability of electric energy loss of the nanocomposites.The real component of permeability shows a trend of increasing in general by the titanium mixed.And the imaginary part of the permeability increased which can improve the ability of magnetic energy loss of the nanocomposites.It shows that the absorbing performance of the composites enhances caused by dielectric loss and magnetic loss changing.5.The nanocomposites reached its maximum reflection loss-30.71 GHz in the case of BaFe_11.8Ti_0.2O₁₉ with CIP quality ratio of 1:0.3 and the coating thickness of 4.5mm.The nanocomposites has a relatively wide absorbing band,and can absorb electromagnetic wave effectively within the multi-band frequency of 4.74-11.115 GHz and 11.71-14.43 GHz by controlling the amount of Ti-doping,the ratio of Ba Fe_12-xTi_xO₁₉ and CIP and coating thickness.6.Trying to prepare the nano fiber of barium ferrite by the electrostatic spinning method.Analysing the crystallinity and the morphology changing of the sample after dealing with the different calcination temperature.