自体模板生长技术制备织构化Z-型六角铁氧体及其室温多铁性调控研究

In order to adapt to the application requirement of high integration, miniaturization and the multifunction in microwave and information technologies, in this project, the synthetic methods, structure, composition, and ferroelectric-ferromagnetic coupling in textured Z-type hexaferrites with potential application value will be investigated, and the theoretic and experimental foundation for the design of new material system will be laid. The hexaferrite template particles with preferred planar orientation will be synthesized by the hydrothermal synthesis method. The phase transition process of hexaferrites and its mechanism will be studied. The relations between ion substitution, preparing method, nanometer size effect, and phase transition from ferromagnetic state to spiral spin order state, and multiferroic properties will be discussed. A new method, the autologous templated grain growth technique will be proposed for the preparation of textured Z-type hexaferrite. The grain growth dynamics and room temperature multiferroic properties for the textures ceramics will be characterized and discussed. The tunability of permeability and ferromagnetic resonance frequency of the textured hexaferrite heterostructures and the probability of the application on the Rf/microwave signal control will be analyzed by experiments and theoretical calculation. The multiferroic properties of these ceramics will be characterized and the mechanisms will be discussed. The phase shifter based on the magnetoelectric coupling of textured Z-type hexaferrites in the frequency range of L and S bands and small antenna will be designed and fabricated.

项目立足于微波与信息技术领域高度集成化、多功能化的应用需求，对具有重要潜在应用价值的织构化Z-型六角铁氧体的合成方法、结构组成、铁电-铁磁耦合机理与应用展开深入研究，为新型室温多铁性材料体系的设计奠定理论和实验基础。采用水热合成法制备平面择优生长的六角铁氧体微晶模板，深入研究相转变过程和机理，探讨离子置换、制备方法、纳米尺寸效应与铁磁-螺旋自旋有序转变和室温多铁性的关系；提出自体模板生长的新颖方法制备织构化Z-型六角铁氧体，并对织构陶瓷的晶粒生长动力学和室温多铁性进行表征和机理探讨；计算分析六角铁氧体磁导率和铁磁共振频率的可调谐性及其在射频/微波信号控制方面的应用可能性；基于织构化六角铁氧体的磁电耦合效应，开展L/S频段用移相器和小型化天线的理论设计与制作。

本项目立足于微波和信息技术领域对多功能化新材料与集成化器件的迫切需求，围绕具有潜在应用价值的单相M-型、Z-型六角铁氧体的水热合成、晶体生长和调控机制、织构化基板制备技术、磁电性能与器件应用开展了深入研究。通过调整原料配方和优化工艺参数，本项目较好地克服了六角铁氧体水热合成中存在的物相组成复杂、晶体形貌难以控制、重复性差等问题，阐明了水热合成过程中出现副产物α-Fe2O3竞争性生长现象的原因和调控机理，分析了离子取代、制备方法与材料磁电性能之间的关系。进一步地，揭示了水热合成M-型六角铁氧体的反应历程，提出并验证了直接水热合成高性能、单相M-型六角铁氧体微-纳粒子的经验公式，揭示了水热合成单相Z-型六角铁氧体过程中的复杂物相演变机制。提出织构化六角铁氧体基板制备的工艺方案，分析探讨了微晶模板、化学组成、煅烧过程等对陶瓷微观组织结构、取向度和磁电性能的影响机理。基于自主研制的基板材料，开展了微波器件的设计与制作方面的应用研究。