Preparation And Microwave Absorption Properties Of Fe Metal Monatomic Carbon Matrix Composites

With the rapid development of modern science and technology,the types and functions of electronic devices are becoming more and more rich,which leads to the problem of electromagnetic interference becoming more and more serious.The commercialization of emerging 5G and 6G wireless devices requires EMI shielding materials that are easy to manufacture,light weight and small thickness.Therefore,how to prepare the above high efficiency microwave absorption materials has become a new research hotspot.Compared with the traditional microwave absorption materials,the new carbon-based materials have the advantages of light weight and strong electrical conductivity.By doping a small amount of Fe atoms into the carbon matrix,the magnetic loss coefficient and dipole polarization of the material can be increased.Combined with the new structure of carbon medium,the best impedance matching can be obtained to achieve more efficient microwave absorption effect.In this paper,three different carbon substrates(porous carbon that carbonized from ZIF-8 and tubular polyaniline,and C₃N₄)were doped with Fe metal atoms,and the effects of their morphologies and structures on the microwave absorption performances were studied.(1)Fe-N/C-m porous carbon composites(Fe-N/C-m)were prepared by carbonization at 900?with ZIF-8 containing different doping amounts of Fe as precursors.Fe atom doping is beneficial for the carbonization sample to maintain the regular 12-hedral porous structure of ZIF-8,and there is no obvious Fe atom aggregation.The microwave absorption characteristics of Fe-N/C-m showed that the doping of appropriate amount of Fe atoms was beneficial to improve the microwave absorption performance of ZIF porous carbon,and Fe-N/C-24 was the best,which was due to the combination of dielectric loss,magnetic loss,multiple reflection and absorption of dipole polarization.(2)Fe-doped tubular polyaniline prepared in weak acid environment was used as the precursor,and then calcined at 900?to prepare Fe atom doped tubular porous carbon(Fe/TPC-m),which was made into tubes to increase the number of reflection and absorption of incident electromagnetic waves.The results show that the introduction of Fe atom can adjust the electromagnetic parameters of the material,thus improving the impedance matching coefficient of carbon materials and improving the wave absorption performance.With Fe/TPC-5,the best wave absorption effect is,when the thickness is 4.0 mm,frequency is 6.80 GHz,the minimum RL is-40.34 GHz,f_E is4.90 GHz.(3)The structure of carbon nitride is similar to that of graphene,with novel dielectric properties,non-toxicity and low cost.The layered structure of C₃N₄ is used to realize multiple reflection of electromagnetic waves,so as to achieve the ability of absorbing electromagnetic waves.By calcining the mixture of DCD and Fe Cl₃ at 575?,the flake-like Fe-doped g-C₃N₄ sample was obtained.The doping of Fe increases the agglomeration between g-C₃N₄ layers.The results show that the sample Fe-C₃N₄-0.25has the best wave absorbing property,with RL of-41.65 d B,f_E is 0.56 GHz when the frequency is 17.20 GHz,the thickness is 9.3 mm.By doping Fe atoms in these three different carbon substrates,the impedance matching and dipole polarization of the materials can be improved,and the microwave absorption capacity of the carbon-based materials can be improved.The advantages of carbon materials and magnetic metals can be effectively combined to obtain more"light"and"strong"microwave absorption materials.