离子取代钛酸铜钇系巨介电陶瓷的结构缺陷与介电响应机制研究

Study of giant dielectric materials have become an interesting topic as energy storage devices. However, the high loss and vague structural mechanism limits its progress. In this project, we intend to prepare ion-substitute Y2/3Cu3Ti4O12 based colossal dielectric ceramics using via solid-state reaction and sol-gel method. The relation among cation design, crystal structure, domain and electrical properties are studied systematically. The concentration of cation and oxygen vacancy can be regulate and control by changing doping, oxygen partial pressure and annealing. The samples estimated the cation vacancy concentration and oxygen vacancy concentration can be obtained. The electrical properties can be measured by the dielectric, impedance, conductance spectrum, electric modulus and activation energy. Grain size, grain boundary and the electric domain of the samples can be achieved using XRD and the Rietveld refinement, AFM, HRTEM, SEM and so on. The crystallite structure and electric domain of the samples will be characterized accurately. By exploring the effects of ion vacancy on crystallite structure, electrical domain and crystal grain, the intrinsic relations among cation vacancy, oxygen vacancy, microstructure, dielectric relaxation and electrical properties of YCTO-based ceramics will be obtained. The corresponding mechanism can also be explored via theoretical analysis. The study also shows a great importance for preparing and improving electrical properties of other dielectric ceramics. The relationship of the electrical properties and microstructure can be analysed so that the micro mechanism of giant dielectric response of YCTO ceramics was revealed for enriching and improving theory and model of the CCTO giant dielectric ceramics. This study will provide new high-performance materials with giant dielectric and low loss properties for lead-free piezo-ferroelectric devices.

高介电常数材料的开发已成为当前储能电容器的研究热点。针对损耗缺乏科学预见以及巨介电响应机理不甚明晰等问题，本项目以高介电常数及低介电损耗的Y2/3Cu3Ti4O12陶瓷作为基元，拟用固相法和溶胶凝胶法制备不等价离子取代Y2/3Cu3Ti4O12系巨介电陶瓷。围绕结构基元修饰与微结构调控的影响因素，从设计不等价离子对阳离子空位和氧空位等点缺陷、晶体结构、晶粒、电畴的影响为切入点，结合多种手段精细表征不等价离子取代样品的宏观电性能、介观结构和微观结构；探索点缺陷与晶体结构、晶格畸变、电畴及电学性能的内在联系，构建结构与性能之间的关联性，阐明晶相结构畸变、电畴结构和畴转变等介观和微观结构因素对陶瓷宏观电性能的影响规律，揭示巨介电响应的物理机制；以期从理论和实验上，证实巨介电相应的结构根源，以此为基础实现电性能的调控，丰富和完善巨介电响应及低损耗理论，为储能器件提供巨介电常数、低损耗陶瓷新材料。

本项目选择具有类钙钛矿结构的ACu3Ti4O12（ACTO，A=Y3+/Cd2+)基巨介电陶瓷作为研究对象，围绕结构基元修饰与微结构调控的巨介电陶瓷的组成设计、微观结构、电性能的相关性研究展开工作。首先，采用固相法和溶胶凝胶法制备不等价离子取代Y2/3Cu3Ti4O12系巨介电陶瓷，系统研究不同取代离子引起的点缺陷对晶体结构、微观形貌（晶粒、晶界及电畴等）及电学性能的内在联系；同时也研究了溶胶凝胶法制备第二组元引入Y2/3Cu3Ti4O12系巨介电陶瓷，优化了制备工艺，研究新组元加入对Y2/3Cu3Ti4O12基巨介电陶瓷的晶体结构、微观形貌及电性能的影响，分别探讨了高性能机制的反应机理。其次，设计不等价离子取代和引入第二组元Cd Cu3Ti4O12系巨介电陶瓷，验证Y2/3Cu3Ti4O12基巨介电陶瓷高性能机制的反应机理。最后，归纳总结ACu3Ti4O12（ACTO，A=Y3+/Cd2+)基巨介电陶瓷介观和微观结构因素对陶瓷宏观电性能的影响规律，揭示巨介电响应的物理机制，丰富和完善巨介电响应及低损耗理论，为储能器件提供巨介电常数、低损耗陶瓷新材料。发表SCI源期刊44篇(标注），获授权专利4个。培养毕业博士生2名，毕业硕士研究生4名。