锆钛酸钡钙无铅压电陶瓷相图及压电性能研究

Quantitative description of the phase composition and crystal structure as well as the contributions of electrons to the piezoelectric is the core for the design of the functional materials, is also the key to achieve the significant breakthrough of the existing materials’ properties and to discover the new materials with high-performance. This project would like to investigate the phase diagram of the BaTiO3-CaTiO3-BaZrO3 system and the structure and polarization of the (Ba1-xCax)(Ti1-yZry)O3 solid solution with the aim to understand the origin of its large piezoelectric constant as well as to design the lead-free piezoelectric ceramics of (Ba1-xCax)(Ti1-yZry)O3: The phase diagram of the BaTiO3-CaTiO3-BaZrO3 system is investigated by combining the experimental measurements on the phase diagram and thermodynamic properties with the first-principle calculations on the thermodynamic properties and the thermodynamic optimization. The morphotropic phase boundary (MPB) between the end-member compositions of BaTiO3-CaTiO3-BaZrO3 system is set up and the law of the phase transitions around the MPB is revealed. The structure and piezoelectric properties of the (Ba1-xCax)(Ti1-yZry)O3 solid solution with the composition near the MPB are studied by the first principle calculation. The results from this project can provide a scientific way for the design of high performance lead-free piezoelectric ceramics related to (Ba1-xCax)(Ti1-yZry)O3.

材料的相组成和组成相的电子结构随成分演变的定量描述是功能材料设计的核心，是实现材料性能重大突破和发现高性能新材料的关键。本项目以BaTiO3-CaTiO3-BaZrO3体系相图和锆钛酸钡钙(Ba1-xCax)(Ti1-yZry)O3固溶体电子结构及压电性能为研究对象，揭示锆钛酸钡钙陶瓷的压电性能来源、优化陶瓷成分：结合相图实验数据、热力学性质实验测量和第一性原理计算及相图热力学计算的集成，建立BaTiO3-CaTiO3-BaZrO3体系相图，确定体系准同型相界，揭示准同型相形成和相变规律；采用X射线衍射和拉曼光谱表征物相组成和组成相的晶体结构，结合实验分析与第一性原理计算，研究(Ba1-xCax)(Ti1-yZry)O3固溶体不同晶体结构与成分相关的电子结构和压电性能。上述研究工作的完成可望为锆钛酸钡钙陶瓷性能优化、成分设计提供一种科学方法并显著减少材料开发的盲目性、节省开发的人力和物力。

材料的相组成和组成相的电子结构随成分演变的定量描述是功能材料设计的核心，是实现材料性能重大突破和发现高性能新材料的关键。本项目以BaTiO3-CaTiO3-BaZrO3体系相图和锆钛酸钡钙(Ba1-xCax)(Ti1-yZry)O3固溶体电子结构及压电性能为研究对象，通过相图实验数据、热力学性质实验测量和第一性原理计算及相图热力学优化计算的集成，建立了BaO-TiO2、CaO-TiO2、BaO-ZrO2等二元体系的相图热力学数据库，外推计算了BaTiO3-CaTiO3-BaZrO3体系相图，揭示了BT-CT-BZ体系相形成和相变规律；建立了多个BaO-Ln2O3体系相图热力学，为进一步系统研究稀土氧化物掺杂对BT-CT-BZ体系微观结构及介电压电性能的影响奠定了基础。采用X射线衍射表征物相组成和组成相的晶体结构，结合实验分析与第一性原理计算，研究(Ba1-xCax)(Ti1-yZry) O3固溶体与成分相关的电子结构和介电、压电性能。以相图热力学计算和第一性原理计算结果为指导，实验制备了关键成分的BCTZ钙钛矿结构压电陶瓷，揭示了钙离子掺杂改善BaTiO3压电性能的原因，获得了压电性能较好的无铅压电陶瓷。