锆钛酸铅反铁电晶体中三临界现象及局部结构与性能关系的研究

反铁电钙钛矿材料在储能、换能和致动等方面具有较高的应用价值，同时围绕这一类型材料的晶体结构演化，存在如反铁电现象产生机制和反铁电-铁电相变等一系列基础科学问题，使得这类材料具有广泛的基础和应用研究价值。本项目计划针对室温下为反铁电相的富锆组分锆钛酸铅晶体，结合申请人前期工作基础，利用晶体学领域快速发展的全散射和漫散射等技术，对其开展长程和短程有序结构研究，尤其厘清升温过程中中间相的发生过程和机理，从而深入研究此相变过程中反铁电相与铁电相的竞争关系以及反铁电相的稳定机理；此外研究这一组分附近的三临界现象，以及由此可能带来的电性能的急剧升高，从而从结构变化角度理解钙钛矿材料三临界现象的产生，以及局部结构演化对物理性能的影响机制，并拓展相关材料的应用前景。

Antiferroelectric perovskite materials have high application values in energy storage, energy conversion, actuation, and other electrical devices. Meanwhile, there are a series of fundamental scientific discussions about the evolution of crystal structures of this type of material, such as the mechanism of occurrence of antiferroelectricity and the antiferroelectric-ferroelectric phase transition. .Aiming towards zirconium-rich lead zirconate-titanate crystal which is antiferroelectric at room temperature, based on the applicant's previous research, we propose to study their long-range and short-range ordered structures, using rapidly developing techniques in the field of crystallography such as total scattering and diffuse scattering. We plan to focus on the process and occurrence mechanism of the intermediate phase, so as to further study the competition between AFE and FE states and the mechanism of AFE stabilization during phase transition. Besides, the structure of the tricritical behavior and the ultra-high electrical properties will also be studied around these compositions in order to understand the existence of tricritical behavior from a structural point of view and to clarify the impact of local-structures on the physical properties, and to expand the application perspective of related materials.