Preparation And Electromagnetic Wave Absorbing Properties Of Titanium Dioxide/Carbon Composites

In recent years,researchers have paid more and more attentions on the carbon materials,due to its low density and the good dielectric properties.Generally,carbon materials are combined with magnetic materials to obtain better impedance matching.However,this is not conducive to the requirements of lightweight of absorbing materials.Based on this,carbon materials derived from three different sources have been combined with TiO₂,which possess low density and strong dielectric loss.In addition,the adjustable electromagnetic absorption performance is realized by the careful design of experimental mechanism.The main contents and results are as follow:?1?The titanium dioxide/carbon composites were obtained by directly pyrolysis of a Ti-based MOF MIL-125?Ti?.Compared with most previous reports of Co-MOF,the synthetic process is easier and the cycle is shorter.More importantly,the TiO₂/C nanocomposites possess good electromagnetic absorption performance.In detail,the minimum reflection loss value of-49.6 dB and broad effective bandwidth of 4.6 GHz?13.4¹8 GHz?can be reached with an absorbent thickness of 1.6 mm.Furthermore,we found that the calcination temperature has effect on the crystals of Titanium dioxide,carbon content,electromagnetic parameters and electromagnetic absorption performance.?2?Although the synthesis process of the first work is simple,and the obtained materials has the advantages of light weight and satisfying effective frequency,but the mechanism of dielectric loss is not clear.Therefore,the second part of this work was to achieve the adaptive electromagnetic wave absorption capability by adjusting the lattice polarization ability of the titanium dioxide.Firstly,we successful adjusted cell volume of the sample by changing the calcining temperature of the sample.And then,the polarization capacity and dielectric constant of the sample were influenced by the change of the cell volume.Finally,the sample annealed at 650 ^oC possesses appropriate lattice polarization and the best microwave attenuation.?3?Interface polarization is also important for electromagnetic absorption besides lattice polarization.Therefore,the third part adopts the mechanism of interface polarization.We have successfully inserted the Titanium dioxide nanoparticles into graphene nanosheets,which can be acted as interfacial polarization point at the interface between Titanium dioxide nanoparticles and graphene nanosheets.And then the amount of interfacial polarization point can adjust the impedance matching and the interfacial polarization capability,which is helpful to improve the electromagnetic absorption of the composite.And finally,when the raw material of tetrabutyl titanate was 1.5 mL,we obtained the excellent absorber,due to the higher interfacial polarization capability and improved impedance matching.In detail,the effective band width can reach 5.2 GHz.In conclusion,the as-prepared Titanium dioxide carbon-based composites not only meet the requirement of the absorbing materials with the excellent performance,widen frequency band,light weight,thin thickness,but also electromagnetic absorption performance can be adjusted by adjusting the dielectric loss capacity.In addition,the methods of this paper are facial,which is of great significance to practical application.