Abstract
In this work, C@Fe3O4 magnetic microspheres were designed and prepared by a novel strategy, and the microwave absorption properties of the materials were investigated. Four kinds of monodisperse P(MAA/St) microspheres with different carboxyl content were synthesized via facile dispersion polymerization. The Fe3O4 nanoparticles were grown on the surface of P(MAA/St) to obtain P(MAA/St)@Fe3O4 microspheres. Using P(MAA/St)@Fe3O4 as the precursors, after vacuum carbonization, C@Fe3O4 were obtained. It was observed that the carboxyl content on the microspheres’ surface increased with the increasing of MAA, which made the magnetic content and maximum specific saturation magnetization of P(MAA/St)@Fe3O4 and C@Fe3O4 increase. The obtained four kinds of C@Fe3O4 microspheres had a particle size range of 4–6 μm. The microwave absorption properties indicated that the magnetic content made a difference to the microwave absorption properties of C@Fe3O4 magnetic microspheres. The microwave absorption properties of materials were determined by controlling dielectric loss, magnetic loss and impedance matching. C@Fe3O4 microspheres exhibited excellent microwave absorption properties. The maximum reflection loss could reach −45.6 dB at 12.8 GHz with 3 mm in thickness. The effective bandwidth was 5.9 GHz with RL < −10 dB. Therefore, C@Fe3O4 microspheres were lightweight and efficient microwave absorption materials.
Highlights
Electromagnetic waves have been widely used in various fields of civil and military applications, such as communications, catering, medical care, stealth, navigation, electromagnetic interference, etc.While bringing convenience to people’s daily lives and providing security for national defense, the deterioration of the electromagnetic environment caused by electromagnetic leakage cannot be ignored.Microwave absorbers have been considered as the most effective way to solve the electromagnetic leakage problem [1,2,3,4,5,6,7]
Among all the microwave absorption materials developed currently, carbon materials [8,9], magnetic materials [10,11] and their composites [12,13] are mainly used for three mechanisms of absorption and loss microwaves by absorbing materials, resistive loss, dielectric loss and magnetic loss mechanisms, respectively
Styrene (St), α-methacrylic acid (MAA), azobisisobutyronitrile (AIBN), sodium citrate, sodium acetate, ferric chloride, ethylene glycol and anhydrous ethanol were purchased from Sinopharm
Summary
Electromagnetic waves have been widely used in various fields of civil and military applications, such as communications, catering, medical care, stealth, navigation, electromagnetic interference, etc.While bringing convenience to people’s daily lives and providing security for national defense, the deterioration of the electromagnetic environment caused by electromagnetic leakage cannot be ignored.Microwave absorbers have been considered as the most effective way to solve the electromagnetic leakage problem [1,2,3,4,5,6,7]. Among all the microwave absorption materials developed currently, carbon materials [8,9], magnetic materials [10,11] and their composites [12,13] are mainly used for three mechanisms of absorption and loss microwaves by absorbing materials, resistive loss, dielectric loss and magnetic loss mechanisms, respectively. Composite particles containing magnetic materials and carbon materials are highly efficient absorbing materials, which combine the characteristics and advantages of both materials. Magnetic carbon particles with various morphologies, particle size scales, pore properties, magnetic contents, and magnetic responsiveness were developed and used as absorbing agents [14,15,16,17,18]. There are various techniques to prepare magnetic carbon composite particles, such as (1) Preparation of magnetic
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