Study On The Microwave Absorption Properties Of Doped Multiferroic Material And Its Periodic Structure

Microwave absorption property of BiFe1-xCoxO3was investigated. A kind of periodic structure was designed and its reflectivity was calculated.BiFe1-xCoxO3samples were prepared by sol-gel process. The crystal structure, morphology and elements of samples were characterized by XRD, SEM and EDS. The complex dielectric constant and complex permeability of the samples were measured by microwave vector network analyzer, the loss tangent and microwave reflectivity were calculated in the frequency range from2to18GHz. When the doping amounts were x=0, x=0.1, x=0.2and the anneal temperature was800℃, the major phase of product was BiFeO3and minor phase was Bi25FeO40, the particle morphology was cube with the size of1.5μm. It was found that the microwave absorption of system is dramatically promoted. When d=1.8mm, x=0.2, the absorption peak and effective band width is-26.5dB and2.08GHz, it possesses excellent microwave absorption characteristics in high frequency. This material possesses dielectric loss and magnetic loss at the same time, but the former is relatively stronger.A kind of cross-shaped aperture periodic structure is designed and the finite-difference time-domain method (FDTD) is used to calculate the reflectivity of materials with this structure. The effect of this periodic structure to the microwave absorption is investigated. Results show that cross-shaped aperture periodic structure can promote the microwave absorption of materials. When the size of cross-shaped aperture is l=16mm, h=2mm, the absorption peak and effective band width is23.2dB and3.2GHz for BiFe0.9Co0.1O3material,-42.5dB and6.5GHz for Sr3Co2Fe24O41material,-63dB and4.3GHz for BiFe0.9Co0.1O3/Sr3Co2Fe24O41bilayer composite.