Nano <sub> Of Fe 3 </ Sub> O <sub> 4 </ Sub> Microwave Absorption Properties Of Composites,

Electromagnetic wave absorption material is a very important military stealth material. It can absorb electromagnetic wave and turn the electromagnetic energy into the heat one or it can make the electromagnetic wave vanished by interfering each other. The effect of the absorption material is to reduce the object's characters from radar and infrared ray. In addition, to prevent electromagnetism pollution, it has important status in environmental department.In this paper, nanosized magnetic particles Fe₃O₄ was prepared by corprecipitation method;nanosized BaTiO₃ was prepared by sol-gel method and polyanilion was prepared by chemical oxidation method. The composite material Fe₃O₄/BaTiO₃ was prepared by physical mixing and the composite material Fe₃O₄/PANI was prepared by in situ polymerization. The samples were characterized by IR, SEM and XRD.The microwave absorption property and electromagnetism parameter of nanosized Fe₃O₄, BaTiO₃ and the composite material were studied in the range of 2¹8GHz. The influence of component's content on microwave absorption property was analyzed. As the components are changed, the permeability and dielectric constant are adjustable. If ferromagnetic Fe₃O₄ and ferroelectric BaTiO₃ were mixed together, the composite material has the attenuation effect of both Fe₃O₄ and BaTiO₃, so the absorbency is advanced. And composite material can remedy defect of single one in some frequencies, so the bandwidth is enlarged.As an absorption material of electric attenuation, PANI is light and its conductivity can be adjusted. But the absorption property of the single material is common. In composite material Fe₃O₄/PANI, when the quality ratio of Fe₃O₄ is less than 35%, the change of electromagnetic parameter is not evident. But when the quality ratio of Fe₃O₄ reaches 35%, the change is evident and the absorption property is the best. And we found absorber's density is very important to the absorption property. As the quality ratio of absorber to olefin is 3/7, the absorption property is the best, absorptive peak's value is -21dB and -10dB width is more than 4GHz.