高性能压电陶瓷相结构设计和缺陷、压电响应机制研究

With the implementation of the strategy of environmental protection consciousness and sustainable development of society, developing high-performance environmental harmony lead-free piezoelectric materials that can substitute PbZrO3-PbTiO3 (PZT)-based ceramics has become a scientific important research hotspot. Recently, texturing of the (K,Na)NbO3-LiTaO3-LiSbO3 (NKN-LT-LS) system ceramics and discovery of novel morphotropic phase boundary (MPB) around tricritical triple point in the Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 (BZT-BCT) system have aroused great confidence on the development of lead-free piezoelectric materials. However, the phase structure design of lead-free piezoelectric materials and their high-performancing, the relationships between crystal defects, domain configuration and piezoelectric properties, and the piezoelectric response mechanism have not been fully disclosed. This project utilizes the research advance of our country in relaxor ferroelectric single crystals, and constructs novel high-performance BZT-BCT-based MPB compositions via composition design and processing tailoring under the guidance of tricritical triple point idea. Then, high-performance single crystalline or textured lead-free BZT-BCT piezoelectric materials are prepared by the reaction solid-state growth method using single crystals as templates. We also investigate the influences of crystal defects, ferroelectric domain configuration and its movement rule, and materials treatment on piezoelectric properties, and establish physical model to describe the piezoelectric response mechanism. Based on this work, we establish effective techniques to modulate crystal structure and optimize piezoelectric performance. This project will promote the understanding of piezoelectric response mechanism of lead-free materials and develop novel lead-free and lead-less perovskite piezoelectric MPB compositions.

随着环境保护意识的提升和可持续发展观念的深入人心，开发高性能无铅压电材料成为电介质领域一项重要科学课题。NKN-LT-LS陶瓷的织构化和BZT-BCT三相临界点的发现，促进了无铅压电材料的发展。然而，无铅压电材料的相结构设计，缺陷、电畴结构与压电性能的关系，压电响应机理的研究还不充分。本项目通过组成设计构建高压电性能、新型BZT-BCT基准同型相界（MPB）相组成。利用我国在压电单晶领域的研究优势，以单晶为模板，通过反应固相生长工艺制备高性能单晶化或织构化BZT-BCT基无铅压电陶瓷。研究晶体缺陷结构、电畴组态及其动态行为、材料后处理工艺对压电性能的影响，建立描述无铅压电材料压电响应机制的物理模型，在此基础上，建立起调控材料结构和优化材料压电性能的有效方法。该项目的研究，对于理解无铅压电材料的压电响应机理、探索新型无铅和少铅系钙钛矿型压电材料新型MPB组成有很好的促进作用。

随着环境保护意识的提升和可持续发展观念的深入人心，开发高性能无铅压电材料成为电介质领域一项重要科学课题。本项目通过组成设计构建高压电性能、新型铁电材料准同型相界（MPB）相组成；利用我国在压电单晶领域的研究优势，以BaTiO3单晶为模板，通过反应固相生长工艺制备高性能压电陶瓷。通过柠檬酸盐法、部分草酸盐工艺、水热法、反相细乳液法制备纳米粒子，以高活性纳米粒子为前驱体，低温烧结结合反应固相烧结制备高性能压电陶瓷。开发了赝三元无铅/含铅压电陶瓷，获得高压电及压电、荧光多功能性能，提出“压电-荧光响应优值”概念评价压电、荧光多功能性能。通过升温拉曼光谱研究压电陶瓷的铁电相变特征，除了在TC处的铁电-顺电相变以外，在TC以下局部结构观察到连续铁电相变，与极性纳米微区（PNRs）发生的从三方相到A型单斜（R-MA），从A型单斜（MA-MC）到C型单斜，再从C型单斜再到四方相（MC-T）的铁电相变有关。通过PFM研究压电陶瓷的微观压电响应机制，通过共焦拉曼显微镜（CRM）研究压电陶瓷的电畴随温度的变化，CRM图像中观察到的岛状畴与PFM中观察到的岛状畴的尺寸一致，揭示了压电陶瓷内存在细小的条状畴，解释了陶瓷的微观结构和宏观电学性能之间的关系。低对称性的纳米极化微区（PNRs）或多相共存都会降低极化偏转和晶格畸变的能垒，这是MPB组成附近压电陶瓷具有优异的介电、铁电和压电性能的原因。该项目的研究，对于理解无铅压电材料的压电响应机理、探索新型无铅和少铅系钙钛矿型压电材料新型MPB组成有很好的促进作用。