Zhao Biao, Liu Junwei, Guo Xiaoqin, Zhao Wanyu, Liang Luyang, Ma Chao, Zhang Rui
Henan Key Laboratory of Aeronautical Materials and Application Technology, School of Mechatronics Engineering, Zhengzhou University of Aeronautics, Zhengzhou, Henan 450046, China.
School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China.
Phys Chem Chem Phys. 2017 Mar 29;19(13):9128-9136. doi: 10.1039/c7cp00629b.
In this article, composites consisting of porous Ni cores coated with boehmite/nickel aluminum oxide nanoflakes were successfully prepared by a versatile method. The crystal constituents and shapes of the boehmite/nickel aluminum oxide nanoflakes were strongly influenced by reaction temperature, and their microwave absorption properties were investigated in terms of complex permittivity and permeability. The results reveal that the composites comprising porous Ni cores coated with boehmite/nickel aluminum oxide synthesized at 180 °C present superior absorption properties. The optimal reflection loss is -44.3 dB (>99.99% attenuation) at 14.4 GHz, and the effective absorption (below -10 dB) bandwidth can be monitored in the frequency range of 5.8-18.0 GHz for an absorber with thickness in the range of 1.5-3.5 mm. The high dissipation capability, good impedance match and multiple reflection of the porous flaky structure are responsible for the improvement in microwave absorption. Moreover, a new absorption mechanism was proposed for the porous structure. In this mechanism, the porous structure serves as a spreading container, which attenuates electromagnetic energy by prolonging the travel path and constrains waves in the void space to gradually consume energy. This method paves a new avenue to design porous magnetic-dielectric absorbing materials.
在本文中，通过一种通用方法成功制备了由涂覆有勃姆石/镍铝氧化物纳米片的多孔镍核组成的复合材料。勃姆石/镍铝氧化物纳米片的晶体成分和形状受到反应温度的强烈影响，并从复介电常数和磁导率方面对其微波吸收性能进行了研究。结果表明，由在180°C合成的涂覆有勃姆石/镍铝氧化物的多孔镍核组成的复合材料具有优异的吸收性能。对于厚度在1.5 - 3.5 mm范围内的吸收体，在14.4 GHz时最佳反射损耗为-44.3 dB（衰减>99.99%），有效吸收（低于-10 dB）带宽可在5.8 - 18.0 GHz频率范围内监测。多孔片状结构的高耗散能力、良好的阻抗匹配和多次反射是微波吸收改善的原因。此外，还为多孔结构提出了一种新的吸收机制。在这种机制中，多孔结构充当一个扩展容器，通过延长传播路径来衰减电磁能量，并将波限制在空隙空间中以逐渐消耗能量。该方法为设计多孔磁电吸收材料开辟了一条新途径。
