TiO2基材料设计与缺陷偶极子团簇的空间构筑、调控和巨介电性能的关联性研究

High performance dielectric material is the key material for new type large capacity ceramic capacitors manufacture. The construction of defect dipole complexs is the main source of realizing the giant dielectric properties of TiO2-based materials. In this project, different kinds of ion are used to prepare co-doped TiO2 materials to construct the spatial configuration of defect dipole complexs combined with first-principles calculation and the effective modulation of defect dipole complexs could be achieved by composition design. The effects of doping ion characteristics such as radius, valence state, shell electron and electronegativity on the spatial configuration of defect dipole complexs and dielectric properties are systematically studied. HRTEM, XPS, EPR, Positron Annihilation spectroscopy, AC impedance and other techniques are used to study the effect of preparation conditions including sintering atmosphere and annealing on point defect concentration as well as defect dipole complexs formation, and to reveal the structural origin and physical properties of the giant dielectric phenomenon in the materials. Finally, the materials with low dielectric loss, giant dielectric constant, good temperature and frequency stability are obtained. This project can provide ideas for the design of high performance TiO2-based dielectric materials. The obtaining of different defect dipole complexs configuration can promote the further understanding of solid defect chemistry and lay a foundation for the application of this material in the field of high capacity capacitors and energy storage.

高性能电介质材料是制造新型大容量陶瓷电容器的关键材料，实现TiO2基材料巨介电性主要取决于缺陷偶极子团簇的构筑。本项目提出采用不同种类离子共掺TiO2材料，结合第一性原理计算，构筑缺陷偶极团簇空间构型，实现组分设计对缺陷偶极子团簇空间构型的有效调控。系统研究掺杂离子特性如半径、价态、壳层电子以及电负性对缺陷偶极子团簇的空间构型和材料介电性能的影响规律；采用HRTEM、XPS、EPR、正电子淹灭谱、交流阻抗等技术研究烧结气氛与退火等工艺条件对材料点缺陷浓度、缺陷偶极子团簇的形成的影响；揭示该材料中巨介电现象的结构根源和物理本征；获得具有良好温度和频率稳定性的低损耗、巨介电常数新材料；本项目的开展可以为高性能TiO2基介电材料的设计提供思路，不同缺陷偶极子团簇构型的获得可以推动人们对固体缺陷化学的进一步认识，并为该材料在高容量电容器和储能领域的应用奠定基础。

本项目选择具有金红石相结构的TiO2材料作为研究对象，开展了TiO2基介电陶瓷的微观结构调节及宏观结构设计、制备、性能及巨介电响应物理机制的研究。结合第一性原理计算，构筑不同空间构型缺陷偶极团簇，调控材料巨介电性能。首先，采用传统固相法制备不同施受主离子掺杂的TiO2介电陶瓷材料，对陶瓷进行微观结构设计并研究预烧温度、烧结工艺以及离子取代对陶瓷微观相结构、显微结构及电性能的影响；并同时研究材料巨介电性能的物理起源，探讨介电性能与介电弛豫行为与掺杂离子价态、半径、电负性的相互关联性。通过以上研究为设计高介电常数、低介电损耗及良好温度稳定性的TiO2基陶瓷材料提供科学依据。其次，通过新型溶胶-凝胶种子法制备了活性高且均匀的Ag，Nb共掺杂TiO2基陶瓷材料前驱粉体及陶瓷：研究Ti浓度对材料前驱粉体微观形貌、材料相结构、陶瓷材料介电性能的影响规律，并将其与传统固相法所制备的Ag，Nb共掺TiO2基陶瓷进行了对比研究。最后，归纳总结了不同掺杂离子对材料介电性能影响规律及不同结构缺陷复合体构筑与巨介电性能的关联性，为储能器件提供高介电常数、低损耗陶瓷新材料，为推动该类材料的实际应用提供了相应的理论科学支持。发表创新性研究论文17篇，标注基金42篇；授权发明专利7项；培养毕业博士生2名，毕业硕士研究生5名。