C/CoLa_xFe_2−xO₄ (with x = 0.1, 0.2, 0.3) composites were compounded by using a high‐temperature hydrolysis. X‐ray Diffraction (XRD) and X‐ray Photoelectron Spectroscopy (XPS) results show that doping of La ions does not alter the spinel crystal structure and partially replaces Fe ions. Results of Field‐Emission Scanning Electron Microscope (FESEM) and Energy Dispersive Spectroscopy (EDS) mapping prove that with the doping of La ions, the grains are refined, and the carbon shell on the surface exists. The effect of doping of La ions on microwave absorption performance of the composites was systematically studied. It is found that an optimal reflection loss (RL) of −49.56 dB is achieved at 4.96 GHz, as the composition is C/CoLa_0.2Fe_1.8O₄. Meanwhile, the sample C/CoLa_0.3Fe_1.7O₄ shows excellent effective absorption bandwidth. Specifically, when the matching thicknesses are 4 and 5 mm, the effective absorption bandwidth is 4 GHz, covering the C band and Ku band, thus realizing multiband absorption. The synergistic effects of the enhanced dipole polarization related to the doping of La ions, improved interface polarization of the core‐shell structure, and the magnetic loss originated from CoLa_xFe_2−xO₄ are responsible for the optimal microwave absorption performance. Therefore, this C/CoLa_xFe_2−xO₄ composite material has the prospect of a multiband high‐efficiency microwave absorber.

中文翻译：

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轻掺杂镧掺杂的铁氧体@葡萄糖基碳复合材料作为有效的多频带微波吸收剂

C / CoLa _x Fe _{2− x} O ₄（x = 0.1、0.2、0.3）复合材料是通过高温水解复合而成的。X射线衍射（XRD）和X射线光电子能谱（XPS）结果表明，掺杂La离子不会改变尖晶石的晶体结构，并且会部分替代Fe离子。场发射扫描电子显微镜（FESEM）和能量色散光谱（EDS）作图的结果证明，掺杂La离子可以使晶粒细化，并且表面上存在碳壳。系统地研究了La离子掺杂对复合材料微波吸收性能的影响。发现，当组成为C / CoLa _0.2 Fe _1.8 O _4时，在4.96 GHz处可获得−49.56 dB的最佳反射损耗（RL）。同时，样品C / CoLa _0.3Fe _1.7 O ₄显示出优异的有效吸收带宽。具体地，当匹配厚度为4mm和5mm时，有效吸收带宽为4GHz，覆盖C频带和Ku频带，从而实现多频带吸收。与La离子掺杂有关的增强偶极极化，核-壳结构的界面极化改善以及CoLa _x Fe _{2- x} O ₄引起的磁损耗的协同效应是最佳微波吸收性能的原因。因此，该C / CoLa _x Fe _{2− x} O ₄ 复合材料有望成为一种多频段高效微波吸收器。