高Snoek极限异质纳米磁环的制备、微波激励机制与宽频带高吸收性能

According to the urgent need of the electromagnetic protection in current civil and military fields, as well as the Snoek’s limit of magnetic absorbing materials, the proposed project is aiming to design and prepare Fe/C/MxFe3-xO(M=Co，Ni) heterostructure nanorings as microwave absorbing materials with high Snoek’s limit and broadband - high absorption. The aforesaid project is based on the following reasons: Designing and controlling over the structure, size, composition, and distribution of the Fe/C/MxFe3-xO (M = Co, Ni) heterostructure nanorings in the nanoscale may give them unique electric and magnetic functions. Owing to Aharonov–Bohm (AB) effect, plasmonic structure, unique polarization and coulping modes, magnetic nanorings can expectantly bring some longing microwave characteristics (i.e., electromagnetic field enhancement, multiple resonance, interference and radiation loss). In this case, Snoek’s limit can be expectantly broken via controlling the interaction between layers of heterostructure nanorings, as well as its surface and interface anisotropy. Moreover, owing to the improved matching and absorbing properties, the “broad band - high absorption” microwave absorbing materials can also be obtained. Therefore, in this project, the microwave –assisted hydrothermal-reduction and solid phase reduction/carbonization/Oswald ripening methods can be developed for selective preparation of Fe/C/MxFe3-xO (M = Co, Ni) heterostructure nanorings; control technology for modulating the microstructure and properties of the above NRs can be established. Moreover, laws about the microstructure, size, composition, and distribution of the heterostructure nanorings influencing on their static magnetic, microwave electromagnetic properties, and Snoek value will be revealed; the microwave excitation mechanism and the new approach for breaking Snoek’s limit will be explored; the heterostructure magnetic nanomaterials with “broadband - high absorption” will be obtained. Therefore, it is of civil significance, military significance, and academic interest.

针对当前民用、军用对电磁防护的迫切性以及传统磁性材料Snoek极限的限制，本项目提出用Fe/C/MxFe3-xO(M=Co，Ni)异质纳米磁环设计和制备“高Snoek极限、宽频带-高吸收”微波吸收材料。这是考虑到：从纳米尺度上设计和控制异质纳米磁环的结构、尺寸、组成和分布有可能赋予其特殊的电、磁功能。纳米磁环的AB效应、等离子体结构、特殊的极化和耦合模式有望带来令人憧憬的微波吸收特性；控制环的双各向异性和界面特性，有望突破Snoek极限的限制，改善匹配特性，获得“宽频带-高吸收”的材料。为此，本项目建立合成异质磁环的微波水热-还原工艺和固相还原/碳化/熟化法及其调控技术；获得异质纳米磁环；揭示结构、尺寸、组成及分布对其静磁、微波电磁特性、Snoek值的影响规律；探索其微波激励机制及突破Snoek极限的新途径，获得“宽频带-高吸收”纳米磁环。因而该研究具有重要的民用、军用意义和学术价值。

针对当前民用、军用对电磁防护的迫切性以及传统磁性材料Snoek极限的限制，本项目提出用碳磁异质纳米磁环设计和制备“高Snoek极限、宽频带-高吸收”微波吸收材料。建立了合成纳米环等材料的微波辅助水热法、水热法、碳热还原、低温混合溶剂法、低温一步化学刻蚀法等多种方法及其调控技术；获得Fe3O4、-Co(OH)2、ZnO微纳米环；Fe3O4/C、Fe/Fe3O4/C、EG/Fe3O4、ZnO环/rGO异质结构环；Co/C/Fe/C、CoNi、CoCu、CuxFe3-xO4@Cu、EG/C/MxFe3-xO4、EG/Fe/Fe3O4、Fe3O4/NiFe2O4/Ni等异质结构；揭示结构、尺寸、组成及分布对其静磁、微波电磁特性的影响规律。研究发现：将大的膨胀石墨（EG）和Fe3O4纳米环复合能有效突破Snoek极限的限制，并获得显著增强的EM参数。大尺寸的环、高的电导率、大的平面各向异性和等离子共振有利于样品的介电常数和磁导率的提高。本项目的研究表明：从纳米尺度上设计和控制异质纳米磁环的结构、尺寸、组成和分布能赋予其特殊的电、磁功能。纳米磁环的AB效应、等离子体结构、特殊的极化和耦合模式能带来令人憧憬的微波吸收特性；控制双各向异性和界面特性，能突破Snoek极限的限制，改善匹配特性，获得“宽频带-高吸收”的Fe3O4/C、Fe/Fe3O4/C、EG/Fe3O4材料。执行期间以通讯作者/或第一作者在国际期刊上发表SCI/EI收录文章26篇，高被引2篇，热点1篇；以第一发明人申请专利22件（授权15件），转让1件。“宽带吸波与隐身材料的设计原理与关键制备方法”获2018教育部高等学校科学研究自然科学奖二等奖。培育研究生7人，获国家奖学金2人，省优秀毕业论文1篇，省优秀毕业生3人；3人读博士。指导研究生和本科生在互联网+、挑战杯等国家A类竞赛中获国家级奖5项，省级12项。