The large-scale preparation of a homogeneous multi-dimensional assembly for microwave absorbers is still believed to be a huge challenge. Herein, a novel class of Fe₂O₃/CNTCM@CN hybrids featuring a three-dimensional (3D) hollow structure (d < 6.88 μm) was successfully fabricated by a facile spray-drying process, followed by an annealing treatment. Magnetic-dielectric composite microspheres were obtained by forcibly assembling 0D γ-Fe₂O₃ nanoparticles, 1D carbon nanotubes (CNTs), and 2D N-doped carbon layers. Due to the unique design of its interface structure and abundant electron conduction paths, Fe₂O₃/CNTCM@CN-2 exhibited excellent microwave absorption (MA) performance. Impressively, the MA value was enhanced to −51.5 dB for Fe₂O₃/CNTCM@CN-2 with a thickness of only 2 mm, and the efficient absorption bandwidth (<10 dB) was broadened to 5.4 GHz with only 10% loading mass; these values have surpassed those of most of the state-of-art MA materials. In this heterogeneous system, remarkable multi-interface regions were built by compressive contact among CNTs, nanoparticles, and N-doped carbon layers, which played a key role in promoting the interfacial polarization. Electron charge density redistribution observed by electron holography further supports the presence of dielectric relaxation locally around these contact interfaces. The special 3D CNT networks and bridged N-doped carbon layers enriched the electron transport routes and optimized the conductivity. In addition, spray-dried Fe₂O₃/CNTCM@CN absorbers at micron-size exhibited a better electromagnetic and size matching. Therefore, this study provides deep insights into a novel strategy for the construction of multi-dimensional hollow assemblies as MA candidates.

中文翻译：

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通过增强介电弛豫来提高多维Fe2O3 / CNTCM @ CN组件的微波吸收性能

仍然认为大规模制备用于微波吸收器的均匀多维组件是巨大的挑战。在此，通过简便的喷雾干燥工艺，然后进行退火处理，成功地制造了具有三维（3D）空心结构（d < 6.88μm）的新型Fe ₂ O ₃ / CNTCM @ CN杂化物。磁-介电复合材料的微球通过强制地装配0Dγ-获得的Fe _2个ö ₃纳米颗粒，1D碳纳米管（CNT），和2D N掺杂的碳层。由于其界面结构的独特设计和丰富的电子传导路径，Fe ₂ O ₃/ CNTCM @ CN-2表现出出色的微波吸收（MA）性能。令人印象深刻的是，Fe ₂ O ₃的MA值提高到-51.5 dB/ CNTCM @ CN-2的厚度仅为2 mm，有效吸收带宽（<10 dB）扩大到5.4 GHz，只有10％的负载质量；这些价值已经超过了大多数最新的MA材料的价值。在这个异构系统中，通过CNT，纳米颗粒和N掺杂碳层之间的压缩接触，建立了显着的多界面区域，这在促进界面极化中起着关键作用。通过电子全息术观察到的电子电荷密度的重新分布进一步支持了在这些接触界面周围局部存在介电弛豫。特殊的3D CNT网络和桥接的N掺杂碳层丰富了电子传输路径，并优化了电导率。另外，喷雾干燥的Fe ₂ O ₃微米尺寸的/ CNTCM @ CN吸收体表现出更好的电磁和尺寸匹配。因此，本研究为构造多维空心组件作为MA候选对象的新型策略提供了深刻的见解。