Preparation And Characterization Of Nano-magnetic Hollow Microsphere And Carbon Composite Materials

In this paper,in order to explore a simple eco-friendly technology to preparenano-magnetic hollow microspheres, CoFe2O4microspheres were synthesized by usingdifferent methods firstly.Then a series of magnetic hollow microspheres doped by nickel,zinc and different rare earth were synthesized by adopting the best preparationtechnology. Magnetic microspheres and carbon nanotubes composite materials weresynthesized to improve the absorbing performance of the material further.The material’smagnetic and absorbing properties between0-6GHz were studied.(1) Spinel cobalt ferrite were prepared by using solvothermal method and two kindsof template method,and the influence of preparation process on the structure,morphology and properties was researched. Results showed that all the products werehollow microspheres structure, and the sample synthesized by using solvothermalmethod distributed uniformly and its particle size was the minimum(50nm).Its magneticproperties and absorbing properties were also better, the Saturation magnetization andcoercive force reached88.45emu g-1and227.84Oe, respectively.And the peak width ofR<-5dB was976MHz.(2) ZnxCo1-xFe2O4, NixCo1-xFe2O4and Zn0.3Co0.7MxFe2-xO4doped by differentproportion of La3+,Ce3+and Nd3+were synthesized by solvothermal method.Theproperties of the sample were characterized using various techniques,such as X-raydiffraction (XRD), scanning electron microscopy (SEM), transmission electronmicroscope (TEM), vibrating sample magnetometer (VSM) and network vector analyzer.The results showed that all the products were hollow microspheres structure,and theparticle size of Zn0.5Co0.5Fe2O4and Ni0.5Co0.5Fe2O4were150nm and200nm. The Saturation magnetization and coercive force of Zn0.5Co0.5Fe2O4microspheres were55.94emu g-1and26.76Oe.While the Saturation magnetization and coercive force ofNi0.1Co0.9Fe2O4reached81.56emu g-1and200.42Oe.The absorbing properties of thetwo sample were also the best,their maximal return loss value reached-17.4dB and-18.4dB respectively.(3) Analyzed the effects of La3+,Ce3+and Nd3+doping amount on the magnetic andmicrowave absorbing properties of Zn0.3Co0.7MxFe2-xO4microspheres. The testing resultsshowed that the doping of La3+and Ce3+could improve the coercive force of cobalt zincferrite,and the doping of the three kinds of rare earth element all could improve themicrowave absorbing of cobalt zinc ferrite. The absorbing properties ofZn0.3Co0.7La0.2Fe1.8O4,Zn0.3Co0.7Ce0.02Fe1.98O4and Zn0.3Co0.7Nd0.2Fe1.8O4were the best,the best return loss value were-16.85dB,-16.62dB and-16.12dB,the peak width ofR<-5dB of Zn0.3Co0.7La0.2Fe1.8O4reached3124.8MHz,better than the doping of Ce3+andNd3+.(4) Co0.3Zn0.7La0.2Fe1.8O4/CNTs were prepared by using solvothermal method,andthe influence of carbon nanotubes amount on the magnetic and microwave absorbingproperties was researched.It has been found that10wt%composite materials obtainedthe best coercive force(107.14Oe) and the best wave-absorbing properties,the maximalabsorbing and peak width of R<-5dB were-28.7dB and3496.8MHz.