(A0.5B0.5)xTi1-xO2陶瓷的点缺陷调控与巨介电机理研究

In this project, we intend to prepare TiO2-based ceramics (A0.5B0.5)xTi1-xO2 (A= In3+, Al3+, Ga3+ cations and B= Nb5+, Ta5+, Sb5+, V5+ cations ) via solid-state reaction method and the search for new high-performance dielectric materials, exhibiting temperature and frequency stable, colossal permittivity (CP > 1000) as well as sufficiently low dielectric loss. The concentration of cation and oxygen vacancy can be changed by various methods, including acceptor/donor doping, changing oxygen partial pressure and annealing. The cation and oxygen vacancy concentration can be estimated by using many methods, such as X ray scattering, HTEM, XPS, EPR, Position Annihilation Technique. By exploring the effects of vacancy on crystallite structure and electrical properties, the intrinsic relations among cation elements, oxygen vacancy and electrical properties of TiO2 based ceramics will be obtained. The corresponding mechanism can also be explored via theoretical analysis. It can be expected that electrical properties of TiO2 based ceramics will be optimized. This combined experimental and theoretical work opens up a promising feasible route to the systematic development of new high-performance CP materials via defect engineering.

本项目制备 (A0.5B0.5)xTi1-xO2 (A= In3+, Al3+, Ga3+等三价金属阳离子；B= Nb5+, Ta5+, Sb5+, V5+等五价金属阳离子)陶瓷，探索出具有良好的温度和频率稳定性的低损耗、巨介电常数(＞1000)新材料；研究化学计量、气氛烧结与退火等工艺条件对材料结构、显微组织与宏观电学性能的影响；采用X射线漫散射、HTEM、XPS、EPR、正电子淹灭谱等技术对材料中的点缺陷进行表征，研究缺陷对材料电学性能影响，结合理论分析，揭示该材料中巨介电现象的结构根源与物理本质；本项目的研究将为TiO2巨介电常数新材料在高容量电容器和储能领域的应用奠定基础，并丰富电介质理论。

本项目主要针对电子器件小型化和高储能密度电容器的发展需求，采用固相反应法制备了一系列TiO2基巨介电陶瓷，通过介电谱的研究，发现此类陶瓷的巨介电现象是由多种介电弛豫共同贡献的，其中“电子钉扎”弛豫峰（10-30 K）对巨介电起主要贡献，通过元素掺杂与退火处理实现了对“电子钉扎”弛豫峰的连续调控；研究了元素掺杂、烧结气氛和退火处理对陶瓷结构、显微组织和介电性能的影响，制备出一系列拥有巨介电常数（ε^'＞104）和低介电损耗（tan δ＜0.05）的(A0.5Nb0.5)xTi1-xO2 (A= In3+, Y3+, Yb3+, La3+, Tl3+)陶瓷；通过引入第二相，提高了陶瓷的击穿场强和介电偏压稳定性，其中 (In0.5Nb0.5)0.5%(Ti0.8Zr0.2)99.5%O2陶瓷满足X7R型电子元器件的要求。本项目还拓展了研究内容，在(A0.5Nb0.5)0.05Ti0.95O2 (A= Al3+, Co3+)陶瓷中发现了磁介电现象。本项目发表SCI论文11篇，其中一区4篇，二区5篇，申报国家发明专利3项（已授权1项）。