Manipulation of perovskite dielectrics with high electric fields and large strains

非技术描述：实现对电子、传感和清洁能源应用中材料的精确、可再现和动态可调控制是一个持续而重要的挑战。 电场在这方面可以是有用的，因为它们可以在这些材料的电子和结构特性中产生戏剧性和令人惊讶的变化。 新技术已经能够将大电场施加到非常薄的层上而不破坏它们，产生巨大但尚未理解的效果。 该项目探讨了基于金属复合氧化物的一类特殊材料的薄膜中引起的结构变化。 目前正在使用X射线散射进行实验，精确地表征应用领域的晶体结构。 本科生和研究生参与国家X射线散射设施的实验，并使用理论计算解释实验结果。 基于该项目概念的推广活动将电场如何改变材料的原子尺度结构的相关概念带给广大受众，包括通过创建在线结构模型。技术优势：高电场有望为研究并最终控制和利用钙钛矿氧化物材料中的结构现象提供新的自由度。 高场有可能诱导结构相变，修改结构对称性，并增加电致伸缩的重要性，在低电场下的影响很大程度上可以忽略不计。 该项目使用新开发的时间分辨X射线微衍射表征技术来探测钙钛矿复合氧化物在高电场和大应变下的性质。 实验正在进行中，以检查最近报道的电场驱动的菱面体和四面体相之间的结构相变的动力学，探测超晶格中的压电性和晶体对称性之间的关系，并探索复杂氧化物晶体中电致伸缩变形的极限。 该项目正在培养本科生和研究生从事科学和技术职业，并使他们在国家X射线散射设施中进行研究。 这些复杂的氧化物材料的原子结构和在这个项目中研究的结构现象，提出了广泛的观众使用一系列互动的在线结构模型。

NON-TECHNICAL DESCRIPTION:It is a persistent and important challenge to achieve precise, reproducible, and dynamically adjustable control of materials with applications in electronics, sensing, and clean energy. Electric fields can be useful in this respect because they can produce dramatic and surprising changes in the electronic and structural properties of these materials. New technologies have resulted in the capability to apply large electric fields to very thin layers without destroying them, yielding large but not yet understood effects. This project probes the structural changes induced in thin films of a particular class of materials based on metal complex oxides. Experiments are being conducted using X-ray scattering, precisely characterizing the crystallographic structure in applied fields. Undergraduates and graduate students are involved in experiments at national X-ray scattering facilities and in the interpretation of the experimental results using theoretical calculations. Outreach activities based on the concepts in this project bring concepts related to how the atomic-scale structure of materials is modified by electric fields to wide audiences, including through the creation of on-line structural models.TECHNICAL DETAILS:High electric fields promise to provide a new degree of freedom in studying and ultimately controlling and exploiting structural phenomena in perovskite oxide materials. High fields have the potential to induce structural phase transitions, to modify the structural symmetry, and to increase the importance of electrostriction, a largely negligible effect at low electric fields. This project uses newly developed time-resolved X-ray microdiffraction characterization techniques to probe the properties of perovskite complex oxides in high electric fields and at large strains. Experiments are underway to examine the dynamics of recently reported electric-field-driven structural phase transitions between rhombohedral and tetragonal phases, probe the relationship between piezoelectricity and crystallographic symmetry in superlattices, and explore the limits of electrostrictive distortion in complex oxide dielectrics. The project is preparing undergraduates and graduate students for careers in science and technology and exposing them to research at national X-ray scattering facilities. The atomic structure of these complex oxide materials and the structural phenomena studied in this project are presented to broad audiences using a series of interactive on-line structural models.