铁铌合金/碳复合纳米胶囊的多重介电极化效应、阻抗匹配设计与GHz频段电磁波吸收机理研究

Ideal electromagnetic wave absorption materials should possess simultaneously properties of both high dielectric loss and high magnetic loss, while in the studies already reported these two terms are highly opposite, thus limiting the design of electromagnetic impendence match. Based on the interfacial dielectric polarizations at nanoscale and the impendence match at gigahertz,in this proposal we expect to synthesize core@shell-type FeNb alloy@carbon nanocapsules using a modified arc-discharge approach, achieving a synergetic enhancement with the integrated multiple advantages of core/shell interfacial polarization, metallic single-atom polarization, heterogeneous phase interfacial polarization, and magnetic resonance. Additionally, based on the Miedema semi-empirical model and the effective heat of formation rule, we will focus on the understanding of the relationship between the microstructures and experimental condition, evaluating the thermodynamic parameters of the Fe-Nb-C system at nanoscale, achieving the synthesis controllability of the FeNb alloy@carbon nanocapsules, and finally uncovering the intrinsic structure configurations of each type of electromagnetic losses. By optimizing the alloy compositions and microstructures, our target is to construct a proper electromagnetic impendence match within a core/shell configuration, providing an effective way to synthesize electromagnetic wave absorption materials combined with multiple functions of high magnetic loss, high dielectric loss, proper impendence match as well as antistatic and heat conduction.

电磁波吸收材料须兼具有高磁损耗和高介电损耗的双重性能，然而一方的强化常是以牺牲另外一方为代价，难以实现阻抗匹配设计。本项目根据纳米尺度界面极化增强现象和GHz频段介电损耗/磁损耗匹配难题，拟利用直流电弧等离子体放电法制备核/壳型铁铌合金/碳复合纳米胶囊，通过控制合金核的尺寸、相界面、以及碳壳中掺杂金属单原子的种类和密度，以期揭示核/壳界面极化、 异质相界面极化、单原子极化和磁畴共振等电磁波损耗效应。同时，以Miedema半经验模型和有效形成热模型为理论基础，阐明微结构与实验条件之间的关联，重新评估电弧放电过程中Fe-Nb-C体系的热动力学参数，达到纳米胶囊的可控制备，进而揭示各个损耗效应的微观结构本源。通过微结构调节各损耗效应之间的平衡，构建合适的阻抗匹配，探索优化电磁波吸收性能的新方法，为未来高磁损耗、高介电损耗、抗静电和热传导一体化的新型GHz频段电磁波吸收材料提供理论基础和实验数据。

开发具有复合电磁波吸收特性的电磁波吸收材料，是应对当前电磁波辐射涉污染，保证通信信息安全以及国民健康的重要手段。本项目利用自主设计的超高冷速直流电弧等离子体设备制备了具有磁@介电复合胶囊结构的电磁波吸收材料，通过控制制备工艺参数，实现了纳米胶囊材料的可控制备。同时，通过对材料进行多界面耦合电磁响应性能研究，揭示了材料中介电极化、界面极化、以及界面耦合等特性与电磁波吸收特性之间的内在关联。尤其是通过制备具有单原子/亚纳米过渡族金属、非金属元素镶嵌/掺杂的核@壳纳米胶囊材料，阐明了单原子极化的演化规律，揭示了不对称异质结构、局域空间电荷重新分配以及宏观介电损耗特性间的关联关系。辅助以第一性原理计算、多物理场模拟等手段，揭示了异质结构、界面耦合、以及多界面散射机制等特性影响材料电磁响应性能的物理本源。同时，我们基于纳米胶囊电磁波吸收材料，开发一系列具有多种不同调控特性的电磁波吸收体，为纳米胶囊材料应用开辟了新道路。