CAREER: Flexoelectric Effect in Ferroelectric Nanowires for High-Performance Nanogenerators

这个教师早期职业发展（CAREER）计划奖的目的是获得在单晶铁电纳米线（NW）中的挠曲电效应（由不均匀应变引起的极化）的基本理解。 理论预测的一个巨大的挠曲电增强的极化在纳米尺度上也将进行测试。 如果这是真的，它将使高效的纳米发电机成为可能，用于纳米级机械能的收集。 这项研究将主要集中在钛酸钡纳米线，因为散装多晶钛酸钡具有最高的挠曲电系数报告。 其他钙钛矿铁电纳米线，如PbTiO 3和Pb（ZrxTi 1-x）O 3（PZT），也将进行研究，以揭示阳离子对挠曲电的贡献。 大部分的研究是使用这些特征良好的纳米线作为基础的国家的最先进的扫描探针显微镜的研究，这将量化的固有的挠曲电系数和测试的挠曲电增强的预测，并建立相和域的贡献的挠曲电效应。 此外，在实验测量的支持下，从理论上预测了纳米尺度的本征挠曲电系数和机械-电能转换效率。这项研究将提供对纳米尺度挠曲电效应的深入的、有实验基础的理解，预计将产生变革性的知识，用于指导纳米发电机的设计，电能转换能力，并且更一般地，将为减小尺寸和增强常规压电和铁电器件的性能建立材料科学基础。 该项目将被纳入大学范围内的计划，以接触高中学生和K-12教师，并吸引来自代表性不足的少数民族（URM）的学生学习科学，技术，工程和数学学科。 将建立一个长期的阶梯式教育计划，指导，指导和培训URM学生从高中生，大学新生，高年级本科生。 这一努力旨在提高学生在威斯康星大学麦迪逊分校的多样性。 与校园研究经验的教师计划的合作将使我们能够推广到高中教师谁是感兴趣的先进的纳米科学和纳米技术，并帮助他们创建或改善科学课程在自己的学校。 一套全面的纳米技术教育的基础上，PI的新纳米技术课程的讲义将开发和在线分发。

The objective of this Faculty Early Career Development (CAREER) Program award is to gain fundamental understanding of the flexoelectric effect (polarization induced by inhomogeneous strain) in single-crystalline ferroelectric nanowires (NWs). The theoretical prediction of a gigantic flexoelectric enhancement of the polarization on the nanometer scale will also be tested. If true, it would make possible highly efficient nanogenerators for nanoscale mechanical energy harvesting. The research will focus mainly on BaTiO3 NWs because bulk polycrystalline BaTiO3 has the highest reported flexoelectric coefficient. Other perovskite ferroelectric NWs, such as PbTiO3 and Pb(ZrxTi1-x)O3 (PZT), will also be studied to reveal the cation contribution to flexoelectricity. The bulk of the research is to use these well-characterized NWs as a basis for state-of-the-art scanning probe microscopy studies, which will quantify the intrinsic flexoelectric coefficients and testing the prediction of flexoelectric enhancement and establish the phase and domain contributions to the flexoelectric effect. In addition, supported by experimental measurements, the nanoscale intrinsic flexoelectric coefficients and the mechanical-to-electric energy conversion efficiencies will be theoretically predicted.This research will provide an in-depth, experimentally grounded understanding of the flexoelectric effect at the nanometer scale, which is expected to generate transformative knowledge for directing the design of nanogenerators with dramatically improved mechanical-to-electric energy conversion capability and, more generally, will establish a materials science basis for reduction in size and enhancement in performance of conventional piezoelectric and ferroelectric devices. This project will be integrated into university-wide programs to reach out to high-school students and K-12 teachers and attract students from underrepresented minorities (URM) to science, technology, engineering, and mathematics disciplines. A long-term stepwise education program will be established for instructing, mentoring, and training URM students from high school students, to college freshmen, to senior undergraduate students. This effort aims at improving the diversity of students at UW-Madison. Collaboration with the campus Research Experience for Teachers program will allow us to outreach to high school teachers who are interested in advanced nanoscience and nanotechnology and to help them create or improve science courses in their own schools. A set of comprehensive lecture notes for nanotechnology education based on the PI's new nanotechnology course will be developed and distributed online.