Preparation And Electromagnetic Properties Of Iron-based Carbon Nanocomposites

Absorbing materials are not only very important in military applications,but also have been used more and more in people's daily life as materials for shielding electromagnetic wave pollution.In this paper,three-dimensional honeycomb-like carbon(Hc C),three-dimensional honeycomb-like carbon-coated nano-iron(Nano-Fe@Hc C)composite materials and three-dimensional honeycomb-like carbon-coated iron-iron nano-oxide(Hc Fe₃O₄@C)composite materials are studied.This paper also studies the electromagnetic wave absorption properties of carbon-coated nano-iron particles(CCIN)and magnetic induction hyperthermia as a drug carrier.Details as follows:(1)Polystyrene(PS)spheres with uniform particle size were prepared by emulsion polymerization method,and then the colloidal crystal template of PS was prepared by slow centrifugation,finally the colloidal crystal template was used to obtain Hc C and Nano-Fe@Hc C composite material and Hc Fe₃O₄@C composite material through different processing methods,characterized by SEM and TEM,confirmed that the prepared Hc C,Nano-Fe@Hc C composite material and Hc Fe₃O₄@C composite material all have a three-dimensional honeycomb-like morphology,while the particle size of the Fe particles in Nano-Fe@Hc C composite material is about 5 nm,and the particle size of the Fe₃O₄ particle in the Hc Fe₃O₄@C composite material is about 10 nm.In addition,XRD,XPS and Raman verified that C in the three materials was amorphous carbon.Through simulating the reflectivity of materials/paraffin composites with different mass fractions,the absorbing properties of the materials can be obtained.As the Hc C mass fraction in the Hc C/paraffin composite increases,the sample's microwave absorption performance also increases.The thicknesses of 2 mm and 3 mm have a minimum reflection loss(RL)of-33.9 d B at a mass fraction of 40%.Among them,when the thickness is 2 mm,Hc C with 40%mass fraction has the widest effective bandwidth of 7.32 GHz.(2)The XRD shows that the prepared Nano-Fe@Hc C composite material has a distinct peak of Fe core,which confirms that the prepared Nano-Fe@Hc C has higher purity.Through simulation calculation the reflection loss of Nano-Fe@Hc C at 2?18 GHz,it is determined that when the mass fraction is 40%and the thickness is 2 mm,the best RL value at 13.88 GHz is-22.4 d B and the effective bandwidth reaches 5.2 GHz.(3)XRD and XPS show that the prepared Hc Fe₃O₄@C composite has a distinct peak of Fe₃O₄ core,confirming the high purity of the prepared Fe₃O₄.VSM indicating that Hc Fe₃O₄@C composite material has permanent magnetic properties.Through BET analysis of the prepared Hc Fe₃O₄@C composite material,its surface area is about 563.1 m²/g,mainly in the form of micropores and macropores.For the Hc Fe₃O₄@C composite material,when the thickness is 3.5 mm,it has the minimum RLvalue at 9.6 GHz,reaching-46.3 d B,and the effective bandwidth at this time has reached 5.04 GHz.When the thickness is 3.0 mm,the minimum RL value at 11.76 GHz is-31.7 d B,and the effective bandwidth reaches 5.4 GHz.In addition,the minimum RL for thicknesses(2.5?5 mm)other than 1mm is-20 d B and below.(4)The microscopic morphology of CCIN,Ba Fe₁₂O₁₉,and Fe powder were observed by SEM,and it was observed that the particle diameters were relatively uniform,satisfying the required particle size scale for magnetotherapy.At the same time,the carbon-coated iron structure of CCIN was further confirmed by TEM,and then the phase composition of CCIN,Ba Fe₁₂O₁₉ and Fe powder was verified by XRD,which can be matched with the standard PDF card.In addition,the specific surface area of CCIN and the mass specific gravity of the components were analyzed by TGA and BET,respectively.The specific surface area and pore type of CCIN through BET are 8.4737 m2/g,and the pore types are mainly mesopores and macropores.The magnetic properties of Ba Fe₁₂O₁₉ particles were measured by VSM.The hysteresis loop indicates that Ba Fe₁₂O₁₉ has strong coercivity and permanent magnetic properties.The reflection loss of CCIN/paraffin composites with different mass fractions was also simulated.For CCIN/paraffin composites with a mass fraction of 60 wt%,the minimum RL obtained at 11 GHz is-58 d B,and the RL<-10 d B bandwidth obtained at 7 to18 GHz.And show good electromagnetic wave absorption performance.Finally,a drug carrier constructed with CCIN,Ba Fe₁₂O₁₉,Fe powder and iodized oil as the base liquid was prepared.The heating efficiency of the drug carrier at different Fe powder contents in vitro and in vivo was studied.In the in vitro fever test,it was found that with the increase of the content of iron powder,the heating rate was faster and faster.The time it takes to warm up to60°C is about 90 s,which meets the temperature and rate required for the treatment of tumor hyperthermia.In magnetic induction hyperthermia in animals,it was found that the temperature could reach 46°C in about 45 min.The temperature can reach about 1 h and within the range of 50-52°C,and the temperature can reach 70.8°C at 150 min.