For the first time, the present work reports the dielectric properties and electromagnetic wave (EMW) absorbing performance of polymer-derived carbon-rich NbC-SiC-C nanocomposites. In our previous work, NbC-SiC-C nanocomposites with the ultra-high temperature ceramic phase NbC as the main phase were synthesized with the allylhydridopolycarbosilane (AHPCS) and niobium pentachloride (NbCl₅) as starting materials. On this basis, divinyl benzene was chosen as carbon-rich source and introduced into the AHPCS and NbCl₅ to form a single-source-precursor. Finally, carbon-rich NbC-SiC-C nanocomposites were successfully synthesized by polymer-derived ceramic approach. Compared with ceramic samples without Nb and with lower carbon content, the carbon-rich NbC-SiC-C nanocomposites show extremely enhanced EMW absorbing performance with minimum reflection coefficient of −51.1 dB at 6.88 GHz for the thickness of 2.27 mm. As a consequence, the resultant carbon-rich NbC-SiC-C nanocomposite has to be considered as structure&function integrated material with excellent EMW absorption performance, which can be applied in hostile environment.

中文翻译：

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单源前驱体衍生的富碳NbC-SiC-C纳米复合材料的介电性能和电磁波吸收性能

本工作首次报道了聚合物衍生的富碳 NbC-SiC-C 纳米复合材料的介电性能和电磁波 (EMW) 吸收性能。_{在我们之前的工作中，以烯丙基氢化聚碳硅烷（AHPCS）和五氯化铌（NbCl 5}）为起始原料合成了以超高温陶瓷相NbC为主相的NbC-SiC-C纳米复合材料。在此基础上，选择二乙烯基苯作为富碳源引入AHPCS和NbCl ₅形成单一来源的前体。最后，通过聚合物衍生陶瓷方法成功合成了富碳 NbC-SiC-C 纳米复合材料。与不含 Nb 且碳含量较低的陶瓷样品相比，富含碳的 NbC-SiC-C 纳米复合材料表现出极强的 EMW 吸收性能，厚度为 2.27 mm 时在 6.88 GHz 时的最小反射系数为 -51.1 dB。因此，所得到的富碳 NbC-SiC-C 纳米复合材料必须被视为结构与功能一体化的材料，具有优异的 EMW 吸收性能，可应用于恶劣环境。