铁酸镍/碳复合中空多壳层结构的制备及吸波性能

采用次序模板法合成了单、双壳层的中空铁酸镍(NiFe₂O₄)材料,通过改变前驱体溶液组成及煅烧条件等因素实现了对产物形貌的调控.在中空NiFe₂O₄颗粒表面原位包覆聚多巴胺,再经过碳化处理,制备了具有中空多壳层结构(HoMS)的NiFe₂O₄/C复合吸波材料;考察了其电磁参数,计算了其吸波性能,分析了不同复合结构对性能的影响.结果表明,中空多壳层结构能够显著降低材料的密度,而碳薄层不仅能够改善其阻抗匹配性,而且提升了材料的反射损耗性能.其中,双壳层NiFe₂O₄/C复合物的吸波性能最佳,当样品厚度为3.5 mm时,材料在8.44 GHz处反射损失最小,为-32.35 dB;当样品厚度为2.0 mm时,材料在14.01～17.69 GHz范围内反射损耗小于-10 d B,有效吸收频宽为3.68 GHz.这些优异性能主要源于独特的中空多壳层结构增加了电磁波多次反射/散射的概率,提供了更多的界面极化,实现了电磁波的快速...

Preparation and Microwave Absorbing Property of NiFe2O4/C Composites with Hollow Multishelled Structure

Hollow nickel ferrite（NiFe₂O₄） materials with single-shelled and double-shelled structures were synthesized by a facile sequential templating approach（STA） to obtain the lightweight and high-performance electromagne-tic wave absorbent. The morphology of NiFe₂O₄ was controlled by changing the slurry constituents and process parameters. Polydopamine（PDA） and carbon were designed and coated on the surface of NiFe₂O₄ through a simple in?situ polymerization and carbonization treatment， forming the composites with hollow multishelled structure（HoMS）. The electromagnetic parameters of NiFe₂O₄/C composites with different morphologies were measured by a network analyzer， and their reflection loss values were calculated by transmission line theory. And the effect of composites’ structures on the performance of electromagnetic absorbing were discussed in detail. The results show that the thin carbon coating significantly improves not only the electromagnetic properties but also the impedance matching， and thus the highly effective reflection loss. The double-shelled NiFe₂O₄/C HoMS composites displayed an excellent microwave absorbing performance. A minimum reflection loss（RL_min） of ?32.35 dB was obtained at 8.44 GHz with absorber thickness of 3.5 mm， along with an effective absorption bandwidth of 3.68 GHz at a 2.0 mm thickness. These results can be attributed to the designable HoMS， which increases the probability of the multiple reflections/scattering and realizes more absorption of microwave besides the interfacial polarization between nanoparticles on the shells.