College of Materials and Technology, Nanjing University of Aeronautics and Astronautics , Nanjing 211100, People's Republic of China.
Jiangsu Laboratory of Advanced Materials and Application Technology , Jiangsu 211100, People's Republic of China.
ACS Appl Mater Interfaces. 2017 May 17;9(19):16404-16416. doi: 10.1021/acsami.7b02597. Epub 2017 May 5.
In this work, two novel flowerlike NiO hierarchical structures, rose-flower (S1) and silk-flower (S2), were synthesized by using a facial hydrothermal method, coupled with subsequent postannealing process. Structures, morphologies, and magnetic and electromagnetic properties of two NiO structures have been systematically investigated. SEM and TEM results suggested that S1 had a hierarchical rose-flower architecture with diameters in the range of 4-7 μm, whereas S2 exhibited a porous silk-flower architecture with diameters of 0.7-1.0 μm. Electromagnetic performances indicated that the NiO hierarchical structures played a crucial role in determining their dielectric behavior and impedance matching characteristic, which further influenced the microwave attenuation property of absorbers based on them. Due to its hierarchical and porous architectures, S2 had higher microwave absorption performances than S1. The maximum R value for sample S2 can reach -65.1 dB at 13.9 GHz, while an efficient bandwidth of 3 GHz was obtained. In addition, the mechanism of the improved microwave absorption were discussed in detail. It is expected that our NiO hierarchical structures synthesized in this work could be used as a reference to design novel microwave absorption materials.
在这项工作中，我们采用面式水热法结合后续的后退火工艺，合成了两种新型的花状 NiO 分级结构，即玫瑰状（S1）和丝带状（S2）。我们系统地研究了两种 NiO 结构的结构、形态、磁学和电磁性能。SEM 和 TEM 结果表明，S1 具有直径在 4-7μm 范围内的分级玫瑰状结构，而 S2 则呈现出直径为 0.7-1.0μm 的多孔丝带状结构。电磁性能表明，NiO 分级结构在决定其介电性能和阻抗匹配特性方面起着关键作用，这进一步影响了基于它们的微波吸收体的微波衰减性能。由于其分级和多孔结构，S2 具有比 S1 更高的微波吸收性能。对于样品 S2，在 13.9GHz 时，R 值最大可达-65.1dB，同时获得了 3GHz 的有效带宽。此外，还详细讨论了微波吸收性能提高的机制。我们期望本工作中合成的 NiO 分级结构可以作为设计新型微波吸收材料的参考。
