Magnetoelectric composites have promising application in electromagnetic wave absorption for their regulatory structures and interfacial interactions. In this research, a facile one-step pyrolyzing procedure was applied to achieve cementite/Fe nanoparticles anchored on nitrogen-doped carbon nanotubes (Fe₃C/Fe/N-CNTs) composites. Fe₃C/Fe encapsulated in nitrogen-doped carbon was generated through in-situ Fe-catalyzed carbothermal reactions.

The obtained magnetoelectric composites displayed excellent microwave absorption properties with a minimum reflection loss of −54.4 dB at 10.4 GHz, a matching thickness of 2.3 mm, and low filler loading (15%). Moreover, even at a low matching thickness of 1.55 mm, the reflection loss was less than −10 dB in the range of 13.7–18.0 GHz, and an effective absorption bandwidth of 4.3 GHz was achieved. The outstanding microwave absorption performance can be summarized as follows. 1) The CNT network enriches the transmission path, enhancing the dielectric loss capability. 2) The hollow one-diameter CNT structure helps strengthen interfacial polarization, optimizing the impedance matching while promoting multiple reflections and scattering. 3) Magnetic Fe₃C/Fe provides a strong magnetic dissipation ability and eddy current losses. 4) The heterogeneous magnetoelectric Fe₃C/Fe/N-CNTs possess multiple interfaces, increasing the interfacial polarization and electromagnetic synergistic losses. This study provides a potential strategy for the large-scale synthesis of low filler loading magnetic–dielectric microwave absorbers.

磁电复合材料因其调节结构和界面相互作用在电磁波吸收方面具有广阔的应用前景。在这项研究中，采用简单的一步热解程序来实现渗碳体/Fe 纳米颗粒固定在氮掺杂碳纳米管 (Fe ₃ C/Fe/N-CNTs) 复合材料上。Fe ₃ C/Fe 封装在氮掺杂碳中是通过原位Fe 催化的碳热反应生成的。

获得的磁电复合材料表现出优异的微波吸收性能，在 10.4 GHz 时的最小反射损耗为 −54.4 dB，匹配厚度为 2.3 mm，填料含量低 (15%)。此外，即使在 1.55 mm 的低匹配厚度下，在 13.7–18.0 GHz 范围内的反射损耗也小于 −10 dB，并实现了 4.3 GHz 的有效吸收带宽。出色的微波吸收性能可概括如下。1）CNT网络丰富了传输路径，增强了介质损耗能力。2）中空单直径碳纳米管结构有助于加强界面极化，优化阻抗匹配，同时促进多次反射和散射。3) 磁性铁₃C/Fe提供了强大的磁耗散能力和涡流损耗。4)异质磁电Fe ₃ C/Fe/N-CNTs具有多个界面，增加了界面极化和电磁协同损耗。该研究为大规模合成低填充量的磁性-介电微波吸收剂提供了一种潜在的策略。