Ba(B'1/3B''2/3)O3复合钙钛矿陶瓷的有序畴结构及微波介电性能调控

The B-site ordered Ba(B'1/3B''2/3)O3 complex perovskites which exhibit excellent dielectric properties and rich microstructural features, have received extensive attentions as low loss microwave dielectric ceramics with great commercial application prospect. However, the realization of ultra-low loss is the key issue to promote their practical applications. On the basis of the preliminary understanding about the cation ordering degree of Ba(B'1/3B''2/3)O3 complex perovskites, this proposal mainly from two aspects of the ordering domain size and the ordering domain boundary, to clarify the structure evolution rule and the corresponding effects on microwave dielectric properties. A physical model about the relation between dielectric loss and ordering domain size will be established to conclude the optimum domain size for Ba(B'1/3B''2/3)O3 complex perovskites. Meanwhile, the static characteristics and dynamic evolution of ordering domain boundary will be systematically investigated by transmission electron microscope to reveal the influence of domain boundary on dielectric loss and the underlying physical mechanism. Accordingly, the ultra-low loss of Ba(B'1/3B''2/3)O3 can be realized by tailoring the ordering domain structure and domain boundary, which is obtained by optimizing the preparation process. This proposal will be instructive for the structure-performance tailoring of ultra-low loss microwave dielectric ceramics, and also lay a theoretical foundation for the new material design.

B位1:2有序的Ba(B'1/3B''2/3)O3复合钙钛矿因其优异的微波介电性能和丰富的微结构特征而受到了广泛关注，是一种极具商业化应用前景的低损耗微波介质陶瓷。而其超低损耗化的实现是推进其实用化需解决的关键难题。本项目在对有序度认识的基础上，拟从有序畴尺寸和有序畴界特征两方面揭示Ba(B'1/3B''2/3)O3复合钙钛矿的有序畴结构演化及对微波介电性能的影响规律。将建立与有序畴尺寸相关的介电损耗物理模型，获得超低损耗Ba(B'1/3B''2/3)O3复合钙钛矿的最佳有序畴尺寸；同时，通过透射电镜对不同有序畴界的静态特征和动态演化展开深入研究，揭示有序畴界特征对微波介电性能的影响规律及其物理机制。最终，通过优化制备工艺，调控其有序畴结构与畴界结构，进而实现超低损耗化。本项目的实施将为超低损耗微波介质陶瓷的结构-性能调控提供指南，并为新材料设计奠定理论基础。

钙钛矿氧化物因其独特的理化特性，是材料领域的研究热点。对钙钛矿材料结构/性能调控原理的探索是实现其性能优化，并推进其实用化应用的关键。本项目完善了Ba(B'1/3B''2/3)O3复合钙钛矿的1:2有序畴结构在透射电镜下的表征分析，确认了1:2 有序结构是由局部的富Nb5+层和贫Nb5+层形成的1:1有序结构演变而来的。结合有序畴结构演化和微波介电性能变化规律，对钙钛矿各Raman峰的归属做了分析，建立了Ba基复合钙钛矿陶瓷的Raman振动模式，有序畴结构和微波介电性能的联系，为深入理解1:2有序钙钛矿的光谱分析理论提供了一定的指导。另一方面，还探索了A位和B位离子置换对钙钛矿氧化物作为超级电容器电极材料的结构和储能特性的影响。本项目设计了一系列基于钙钛矿氧化物的电极材料，通过对其晶体结构和缺陷特征的深入分析进一步了解氧嵌入型电化学机理在不同钙钛矿结构中的应用，完善了钙钛矿氧化物的电化学储能机理。本项目的研究成果大大丰富了钙钛矿氧化物的结构/性能调控理论，为其性能优化提供理论指导，促进其作为各类电子元器件的关键材料的应用。