Ni Zhentao, Lu De, Jia Shuhai, Su Lei, Wang Lei, Guo Pengfei, Dai Zhiwei, Guo Jinyu, Niu Min, Peng Kang, Wang Hongjie
State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
ACS Appl Mater Interfaces. 2025 Jul 30;17(30):43189-43198. doi: 10.1021/acsami.5c07192. Epub 2025 Jul 16.
Balancing superb impedance matching and strong attenuation capacity still remains a critical challenge in the development of microwave-absorbing materials (MAM). Here, we report a multiscale design strategy to fabricate gradient impedance all-ceramic aerogels, achieving both excellent impedance matching and enhanced attenuation. The composite aerogel, composed of hybrid SiC/SiN nanowire networks, features a multilayer gradient impedance structure that ensures a smooth electromagnetic wave transition from free space to the material, minimizing reflection while enabling efficient wave attenuation. Benefiting from this design, the aerogel exhibits ultralow density (15 mg/cm), an outstanding effective absorption bandwidth (EAB) of 11.2 GHz, and a minimum reflection loss (RL) of -46.2 dB at room temperature. The superior absorption performance originates from the synergistic effect of gradient impedance matching and multiple electromagnetic wave loss mechanisms, including conduction loss, polarization loss, and multiple scattering and reflections. Furthermore, the inherent thermal stability of ceramics allows the aerogel to retain remarkable absorption performance after oxidation at 1300 °C, with an EAB of 9.52 GHz and RL of -43.4 dB. This work not only demonstrates the potential of gradient impedance aerogels for extreme environments but also provides a strategy for the design of a high-performance MAM.
在吸波材料（MAM）的开发中，平衡出色的阻抗匹配和强大的衰减能力仍然是一项关键挑战。在此，我们报告一种多尺度设计策略，用于制造梯度阻抗全陶瓷气凝胶，实现优异的阻抗匹配和增强的衰减。由混合SiC/SiN纳米线网络组成的复合气凝胶具有多层梯度阻抗结构，可确保电磁波从自由空间到材料的平滑过渡，在实现高效波衰减的同时将反射降至最低。受益于这种设计，该气凝胶具有超低密度（15 mg/cm），在室温下具有11.2 GHz的出色有效吸收带宽（EAB）和-46.2 dB的最小反射损耗（RL）。优异的吸收性能源于梯度阻抗匹配与多种电磁波损耗机制（包括传导损耗、极化损耗以及多次散射和反射）的协同效应。此外，陶瓷固有的热稳定性使气凝胶在1300°C氧化后仍能保持出色的吸收性能，EAB为9.52 GHz，RL为-43.4 dB。这项工作不仅展示了梯度阻抗气凝胶在极端环境中的潜力，还为高性能MAM的设计提供了一种策略。
