Synthesis And And Electromagnetic Properties Of Light Weight Composites

With the large-scale popularization ofcommunication appliancesand electronic tools in scientific,commercial,industrialand military fields,the emerged electromagnetic interference?EMI?has become a seriouscrisis.EMIcan harm the health ofhuman beings,especially expectant mothers and children and pollute the environment In order to effectivelysolve the serious problemscaused by EMI many studies have focused onmicrowave absorption materials.However,until now,a single absorption material that can act as a microwave absorber with strong absorption,wide workingfrequency bandwidth and thin thickness has not been produced.In this work,MnFe₂O₄/HGS?CoFe₂O₄/HGS?CoFe₂O₄/MWCNTscomposites were prepare by chemical coprecipitation.The structure and morphology of the MnFe₂O₄/HGS?CoFe₂O₄/HGS?CoFe₂O₄/MWCNTscomposites werecharacterized by X-ray diffraction?XRD?,field emission scanning electron microscopy?FE-SEM?and transmission electron microscopy?TEM?.The complex permittivity and permeability of the CoFe₂O₄/MWCNTs composites were measuredand then the reflection loss?RL?wascalculated in the frequency range of 1--18 GHz.In SEM images CoFe₂O₄ nanoparticles were coated on the surface of MWCNTs evenly.The sample ?m=70%?the mass fraction ofMnFe₂O₄ is denoted as?m hereafter?has the minimum reflection loss of-35.5dB at 6.9GHz at the thickness of 6.9mm and the effective bandwidth?RL?27?-10dB?is even wider than-4.6GHz,ranging from 3GHz to 5.9GHz and 13.8GHz to 15.5GHz.The minimum reflection loss of CoFe₂O₄/MWCNTs sample?7.5%?with thickness of 3.1mm are-62.22 dB.And the effective bandwidth CoFe₂O₄/MWCNTs sample?5.0%?is up to 3.2GHz.These samplesexhibit excellent microwave absorption properties in terms ofthin thickness,broad frequency,and strong absorption.