Preparation And Microwave Absorbing Properties Of Highly Ordered C-based Metal Oxide Materials

In this paper,the metal organic frameworks MOF-5 was obtained by solvothermal method as precursor,and the ZnO/C composites were prepared by heat treatment under nitrogen gas.Fe³⁺ doped MOF-5 was prepared by solvothermal method.ZnO/ZnFe₂O₄/C composite absorbing material was successfully obtained after heat treatment.The phase,microstructure,magnetic properties and microwave absorbing properties of the samples were analyzed by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FTIR?,vibrating sample magnetometer?VSM?and vector network analyser?VNA?.SEM image analysis shows that the size of the prepared ZnO/C material is about25?m,which is a complete cube structure which is completely stacked by the sheet.The thickness of the thin film is about 20 nm,and the elements of Zn,O and C are evenly distributed.It is found that the ZnO/C composites have two infrared absorption peaks at 6-8?m and 23-24?m,and the absorbance is about 45% and 65% respectively.The results of microwave absorption show that the best reflection loss At 17.18 GHz at-14.1dB,the relative thickness of 7mm,the frequency bandwidth of 16.8GHz-17.67GHz;In addition,the ZnO/ZnFe₂O₄/C composite absorbing materials were prepared by using Fe³⁺ doped MOF-5 as precursors.SEM results showed that ZnO/ZnFe₂O₄/C was a cubic hollow honeycomb structure,And the magnetic properties of the ZnO/ZnFe₂O₄/C composites are paramagnetic-superparamagnetic properties at room temperature,and their saturation magnetization is about 8 emu / g,the residual magnetizatio?Mr?n and the coercivity?Hc?is about 2.13 KA / m.The results show that ZnO/ZnFe₂O₄/C composites have three strong infrared absorption peaks at 6-7?m,16-18?m and 23-24?m,and the absorbance is 70%,83% and 89% respectively.The results show that ZnO/ZnFe₂O₄/C composites have an attenuation of less than-10 dB when the coating thickness is 7.5-7.9mm,and the corresponding absorption band is14.62-16.05 GHz.The maximum reflectivity appears at-13.98 dB at 14.5 GHz,corresponding to a thickness of 7.6 mm.The results show that the ZnO/C materials are designed to be lightweight and have a large surface area,and the multi-scattering is caused by the porous structure.These scattering and electron polarization,interfacial polarization and relaxation affect the absorption and attenuation of the electromagnetic wave,enhanced the absorbing performance.The ZnO/ZnFe₂O₄/C composite absorbing materials doped with Fe³⁺ not only have the porous pore structure of ZnO/C material but also improve the electromagnetic parameters so as to broaden the absorption band width on the basis of good microwave absorption performance and further improve the infrared absorption rate.