Preparation And Properties Of Ni_0.5Zn_0.5Fe₂O₄ Ferrite-based Microwave Absorption Materials

With the rapid development of science and technology and the widespread use of various types of electronic products,serious electromagnetic pollution has caused harm to the development of society and human life.Therefore,it is urgent need to develop efficient electromagnetic wave absorption materials.Ni-Zn ferrite is a common microwave absorption material with disadvantages such as high density and narrow band width.In this article,a series of Ni-Zn ferrite-based materials were prepared and their microwave absorption properties were investigated from the composition and structural modulation of Ni-Zn ferrite in order to achieve the requirements of thin thickness,light mass,strong absorption and wide frequency band of microwave absorption materials.The specific research and conclusions are as follows:（1）Ni_0.5Zn_0.5Fe₂O₄ was prepared by the sol-gel method of self-propagation,and the effects on the phase structure,microscopic morphology,elemental state,magnetic properties,and microwave absorption properties of the materials were observed by varying the sintering temperatures（1150℃,1250℃,1350℃,and 1450℃）.The results show Ni_0.5Zn_0.5Fe₂O₄ ferrite sintered at 1250℃ has the minimum reflection loss value,which is-49.79 d B at the thickness of 5.0 mm,and Ni_0.5Zn_0.5Fe₂O₄ ferrite sintered at1350℃ has the widest effective absorption bandwidth,which is 9.55 GHz at the thickness of 2.5 mm.The ultra-wide effective absorption bandwidth seen in the sample is mainly due to the presence of two reflection loss peaks in the material.The first reflection loss peak exists in the frequency range of 2-5 GHz due to the high magnetic loss of the sample.And the other reflection loss peak occurs in the 9-13 GHz frequency range,which is consistent with the quarter-wavelength model and is caused by the interferometric phase extinction of the electromagnetic wave.（2）Ni_0.5Zn_0.5Fe₂O₄/C hollow spheres were prepared by hydrothermal method and further annealing,and the effects of annealing temperature on the phase structure,morphology and microwave absorption performance of the samples were investigated.The best microwave absorption performance was achieved for the sample annealed at700℃,with the minimum reflection loss value of-35.79 d B at the thickness of 2.5 mm and the effective absorption bandwidth of 5.29 GHz at the thickness of 2.0 mm.（3）A composite material with hollow spheres Ni_0.5Zn_0.5Fe₂O₄ as the core and magnesium silicate as the shell layer was prepared by the hydrothermal method and microwave absorption performance was studied.The minimum reflection loss value of Ni_0.5Zn_0.5Fe₂O₄ hollow sphere reaches-28.23 d B at the thickness of 5.0 mm,and the effective absorption bandwidth is 2.16 GHz.And the minimum reflection loss value Ni_0.5Zn_0.5Fe₂O₄@Mg Si material is-15.06 d B at the thickness of 5.00 mm,and the effective absorption bandwidth is 2.74 GHz.