POWRE: Hysteresis, Domain Switching and Phase Transformations in Ferroelastic Perovskite Ceramics

该项目通过弯曲技术、微和纳米压痕测试以及x射线相位分析、拉曼光谱和电导率测量等方法的组合来解决钙钛矿陶瓷的机械性能问题。该项目旨在了解迟滞效应（畴重定向、相变等）与钙钛矿陶瓷力学行为之间关系的基本知识，提高对钙钛矿强度、硬度和断裂韧性的理解，并发现新的增韧机制。该方法涉及研究不同的一阶或二阶相变，如非金属-金属相变、马氏体相变、有序-无序相变，伴随着体积变化，导致钙钛矿在加载过程中增韧。最重要的目标是确定在压痕和弯曲试验期间是否存在畴重定向或相变。在卸载样品时发生的可逆转变的研究也有望是可行的。将获得有关钙钛矿的畴重取向、相变、金属化的新知识。与结构性能相关的关键性能将在微结构和相组成优化的反馈回路中进行测量。这是在研究和教育领域妇女专业机会（POWRE）计划下提供的一项研究加强补助金。该项目在关键时刻提供支持，帮助PI在从欧洲搬到美国的短暂中断后重新建立她的职业生涯，并将增强PI在女性代表性不足的领域取得成功的能力，使她成为机械工程领域其他女性的榜样。拟议的研究还将产生教育影响，培养具有广泛经验的学生。这项研究将在与陶瓷材料行为特别相关的基础水平上贡献基础材料科学知识，并协助研究和教育的整合。该项目由材料研究部和MPS OMA（多学科活动办公室）共同支持。＊＊＊

This project addresses mechanical performance of perovskite ceramics using a combination of methods such as bending techniques, micro- and nano-indentation tests coupled with X-ray phase analysis, Raman spectroscopy and electrical conductivity measurements. The project seeks fun-damental knowledge about relationships between hysteresis effects (domain reorientation, phase transformations, etc.) and mechanical behavior of perovskite ceramics, improved understanding of perovskite strength, hardness and fracture toughness and discovery of new toughening mecha-nisms. The approach involves the study of different first or second order phase transitions, such as nonmetal-metal transitions, martensitic transitions, order-disorder transitions, accompanied by volume changes, leading to toughening of perovskites during loading. A paramount goal is to determine the presence of domain reorientation or phase transformation during indentation and bending tests. Studies of reversible transitions that occur upon unloading of samples are also ex-pected to be feasible. New knowledge about domain reorientation, phase transformation, metalli-zation in perovskites will be gained. Key properties relevant to structural performance will be measured within a feedback loop to microstructural and phase composition optimization.%%% This is a research enhancement grant made under the Professional Opportunities for Women in Research and Education (POWRE) program. The project provides support at a critical time, helping the PI to re-establish her career after a brief interruption as she moved from Europe to the US, and will enhance the PI's ability to succeed in an area where women are underrepresented, allowing her to serve as a role model for other women in mechanical engineering. The proposed research will also have an educational impact, training students with a breadth of experience. The research is expected to contribute basic materials science knowledge at a fundamental level of special relevance to the behavior of ceramic materials, and to assist with the integration of re-search and education. The project is co-supported by the Division of Materials Research, and the MPS OMA(Office of Multidisciplinary Activities). ***