Microwave Absorption Properties Of Magnetic Metal Oxide Hollows And Their Carbon Composites Prepared By Template Method

In recent years,the nano-metal oxide hollow spherical shell structure materials have shown the characteristics of low density and high specific surface area,the surface permeability is very strong and the shell thickness is in the nanometer scale scope and so on many merits.Transition Metal Oxides(Ni O)with high permittivity,permeability,stability and Curie temperature are often used as wave-absorbing materials.However,the morphology of Ni O is changed on the basis of its original properties,the preparation of magnetic metal oxides as hollow spherical shells greatly improves their properties.In this paper,carbon spheres with different thickness were prepared by calcining different elements(Ni and Fe)to remove the templates,and then the metal oxide hollow shells with different thickness and their carbon composites were prepared,and the absorption of electromagnetic wave is tested.The main contents are as follows:1.Carbon Spheres prepared from glucose were used as templates,by adding different proportions of nickel nitrate hexahydrate solution and mechanically stirring at 80°C in water bath,the ions are uniformly bonded on the surface of carbon template under the action of self-assembly,finally,Ni O hollow shells and its carbon composites were obtained by removing the templates by calcining in different atmospheres.The results of SEM and TEM show that the metal oxide hollow Shell is formed by the dense arrangement of nano-sized particles,and the thickness of the shell increases slightly with the increase of the concentration of metal salt solution.Combined with the electromagnetic parameters of the sample,the results show that Ni O/Cs-2/1-Ar has the best absorbing performance at the thickness of 1.5 mm,the minimum reflection loss(RL)can reach-63.8 d B,and the absorbing bandwidth can reach 7.1 GHz.2.Using carbon spheres as templates,adding different proportions of ferric nitrate solution,mechanically stirring at a certain temperature,adhering to the template surface by ion self-assembly technology,and finally,removing carbon spheres by calcination,Fe2O3 hollow Shell and its carbon composite were obtained.Four samples were obtained by adjusting the solubility of iron salt solution.The results of SEM and TEM show that the shell thickness increases with the concentration of salt solution increasing.The results show that Fe2O3/Cs-2/1 shows the best absorbing properties,and the minimum reflection loss(RL)-40.1 d B at the thickness of 2.8 mm is reached,the effective absorption bandwidth is 4.63 GHz(6.68-11.31 GHz).In addition,in the range of 2.0-4.0 mm thickness and in the frequency range of 7.5-16.2 GHz,the reflection loss intensity can reach <-20dB.