Collaborative Research: Martensitic Transformations in Paraelectric Shape Memory Ceramics Activated by an Electric Field

合作研究：电场激活顺电形状记忆陶瓷中的马氏体转变

• 批准号: 2204644
• 负责人: Eric Homer
• 金额: $ 29.84万
• 依托单位: Brigham Young University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2204644&HistoricalAwards=false
• 关键词: Collaborative; Research; Martensitic; Transformations; Paraelectric

Non-Technical SummaryA martensitic transformation is a structure change that takes place in some crystalline materials, in which the atoms spontaneously and rapidly reshuffle into a new crystal structure in a coordinated way. In some materials this transformation is reversible, so that the material can repeatedly transform back and forth between two shapes, giving rise to the property of “shape memory”. In a martensitic ceramic like zirconia, the shape change is very large (elongating and contracting a shape by ~10%) and it also exerts very large forces. For this reason, shape memory materials are like “solid-state engines”, able to do work on their surroundings as actuators. What is more, it has been recently discovered that shape memory zirconia can be transformed by applying electric fields to it, which opens the door to electronic control over shape memory. With support from the Ceramics Program in the Division of Materials Research, this project investigates the new property of electrical shape memory in ceramics and develops tools to discover and design new ceramic materials that exhibit this property. The project consists of computational and theoretical efforts to understand how different parameters affect the martensitic transformation, led by Prof. Homer at Brigham Young University, and an experimental effort to validate the phase transformation theory for different orientations of the crystals, temperatures, and applied electric fields. This research to synthesize and test new prospective shape memory ceramics is carried out in Prof. Schuh’s research group at the Massachusetts Institute of Technology. This research has implications for actuator device technologies, which have not been as easily miniaturized as other electronic technologies. Additionally, the project will also provide scientific training for two PhD students, one at each institution, and outreach activities will involve a collaborative effort to strengthen the roll out of a Materials Science minor program at BYU to unify materials-oriented students that are spread across different majors on campus.Technical SummarySupported by the Ceramics Program in the Division of Materials Research, this project investigates a new class of shape memory ceramics in which the classical advantages of shape memory (the ability to do large amounts of mechanical work through a solid state phase transformation) are paired with a new mechanism for activating that property (an electric field-driven paraelectric-to-paraelectric phase transformation). Besides developing an entirely new class of “paraelectroactive” ceramics that can perform meaningful mechanical work and expanding the portfolio of electroactive ceramics, the research also has implications for the theory of phase transformations more broadly. The research involves four interrelated tasks: (1) developing and validating thermodynamic models that incorporate the coupled influence of electrical-thermal-mechanical energy on a paraelectric-to-paraelectric martensitic transformation; (2) examining the role of crystal orientation and anisotropic material properties on the predicted and observed phase transformation conditions; (3) exploring the role of dopants to control the transformation conditions and enable room temperature operation of this phenomenon; (4) expanding the materials-scope of the phenomenon by discovering alternative (non-zirconia) shape memory ceramics that exhibit paraelectric-paraelectric martensitic transformations. These tasks are collaboratively investigated with a primarily experimental effort in Prof. Schuh’s research group at the Massachusetts Institute of Technology and Prof. Homer’s research group mostly carrying out theoretical effort at Brigham Young University.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

马氏体相变是发生在某些晶体材料中的一种结构变化，其中原子自发地、快速地以协调的方式重新洗牌成新的晶体结构。在某些材料中，这种转换是可逆的，因此材料可以在两种形状之间反复转换，从而产生“形状记忆”的性质。在像氧化锆这样的马氏体陶瓷中，形状变化非常大（拉长和收缩形状约10%），并且它也施加非常大的力。出于这个原因，形状记忆材料就像“固态发动机”，能够像驱动器一样在周围环境中工作。更重要的是，最近发现，形状记忆氧化锆可以通过施加电场来改变，这为电子控制形状记忆打开了大门。在材料研究部陶瓷项目的支持下，该项目研究陶瓷中电形状记忆的新特性，并开发工具来发现和设计具有这种特性的新陶瓷材料。该项目包括计算和理论工作，以了解不同参数如何影响马氏体相变，由杨百翰大学的荷马教授领导，以及实验工作，以验证不同取向的晶体，温度和外加电场的相变理论。这项合成和测试新型形状记忆陶瓷的研究是由麻省理工学院的Schuh教授的研究小组进行的。这项研究对执行器装置技术具有重要意义，因为它不像其他电子技术那样容易小型化。此外，该项目还将为杨百翰大学的两名博士生提供科学培训，每所大学一名博士生。此外，拓展活动还将涉及合作，加强杨百翰大学材料科学辅修课程的推出，以统一分布在校园不同专业的以材料为导向的学生。在材料研究部陶瓷项目的支持下，该项目研究了一类新的形状记忆陶瓷，其中形状记忆的经典优势（通过固态相变进行大量机械工作的能力）与激活该特性的新机制（电场驱动的准电到准电相变）相匹配。除了开发一种全新的“副电活性”陶瓷，可以进行有意义的机械功和扩大电活性陶瓷的组合外，该研究还对相变理论有更广泛的影响。该研究涉及四个相互关联的任务：(1)建立和验证包含电-热-机械能对拟电-拟电马氏体相变耦合影响的热力学模型；(2)考察晶体取向和材料各向异性对预测和观察到的相变条件的影响；(3)探索掺杂剂对控制相变条件的作用，使这一现象能够在室温下运行；(4)通过发现具有准电-准电马氏体转变的替代（非氧化锆）形状记忆陶瓷，扩大了这一现象的材料范围。这些任务是由麻省理工学院的Schuh教授的研究小组和杨百翰大学的Homer教授的研究小组合作进行的，主要是实验工作。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。