Qin Ming, Zhang Limin, Zhao Xiaoru, Wu Hongjing
MOE Key Laboratory of Material Physics and Chemistry under Extraordinary School of Physical Science and Technology Northwestern Polytechnical University Xi'an 710072 China.
Adv Sci (Weinh). 2021 Feb 8;8(8):2004640. doi: 10.1002/advs.202004640. eCollection 2021 Apr.
Defect engineering is an effective approach to manipulate electromagnetic (EM) parameters and enhance absorption ability, but defect induced dielectric loss dominant mechanism has not been completely clarified. Here the defect induced dielectric loss dominant mechanism in virtue of multi-shelled spinel hollow sphere for the first time is demonstrated. The unique but identical morphology design as well as suitable composition modulation for serial spinels can exclude the disturbance of EM wave dissipation from dipolar/interfacial polarization and conduction loss. In temperature-regulated defect in NiCoO serial materials, two kinds of defects, defect in spinel structure and oxygen vacancy are detected. Defect in spinel structure played more profound role on determining materials' EM wave dissipation than that of oxygen vacancy. When evaluated serial Co-based materials as absorbers, defect induced polarization loss is responsible for the superior absorption performance of NiCoO-based material due to its more defect sites in spinel structure. It is discovered that electron spin resonance test may be adopted as a novel approach to directly probe EM wave absorption capacities of materials. This work not only provides a strategy to prepare lightweight, efficient EM wave absorber but also illustrates the importance of defect engineering on regulation of materials' dielectric loss capacity.
缺陷工程是一种操控电磁（EM）参数并增强吸收能力的有效方法，但缺陷诱导介电损耗主导机制尚未完全阐明。在此首次证明了基于多壳尖晶石空心球的缺陷诱导介电损耗主导机制。针对系列尖晶石独特但相同的形态设计以及合适的成分调制，可以排除偶极/界面极化和传导损耗对电磁波耗散的干扰。在NiCoO系列材料的温度调控缺陷中，检测到两种缺陷，即尖晶石结构缺陷和氧空位。尖晶石结构缺陷在决定材料的电磁波耗散方面比氧空位发挥了更深刻的作用。当将系列钴基材料评估为吸收剂时，由于其在尖晶石结构中有更多缺陷位点，缺陷诱导的极化损耗导致了基于NiCoO的材料具有优异的吸收性能。研究发现电子自旋共振测试可作为一种直接探测材料电磁波吸收能力的新方法。这项工作不仅提供了一种制备轻质、高效电磁波吸收剂的策略，还阐明了缺陷工程对调节材料介电损耗能力的重要性。
