Origin of the Electric Field-induced Strain in Lead-free Piezoelectric Ceramics

非技术描述：压电材料在受到电场作用时会改变其尺寸，因此其应用范围从气体点火器、扬声器电话到医疗超声成像系统。在目前的商业压电器件中，这些材料包含约60重量%的中铅的由于铅的毒性，许多国家最近的立法限制了它的使用。本研究旨在揭示无铅陶瓷压电变形的基本机理。研究结果将最终导致陶瓷的生产，以取代含铅压电材料。因此，预计将对健康和环境产生重大影响。除了让来自代表性不足群体的研究生和本科生参与其中外，该项目还将通过向科学奥林匹克（http：//soinc.org/）团队学生讲授压电器件，直接使爱荷华州艾姆斯当地学校的K-12教育受益。技术规格：Pb（Zr 1-xTix）O3（PZT）中铅的环境问题引起了世界各国对无铅压电陶瓷的广泛研究。以前的研究人员认为，两个最好的系统，陶瓷的基础上（K0.5Na0.5）NbO 3和那些基于（Bi0.47Na0.47Ba0.06）TiO 3，具有完全不同的压电变形机制，从那些在PZT。有限的证据表明，从电场诱导相变的应变变得显着。利用PI独特的原位透射电子显微镜技术，该项目旨在揭示这些无铅陶瓷中在外加电场下产生的应变的起源。结合实验工作，基于密度泛函理论方法的计算建模也计划。该项目的成果有望为开发具有高且温度稳定的压电性能的新型无铅组合物提供重要指导。该项目旨在对研究生和本科生材料科学教育产生广泛的影响。本科生，特别是那些来自代表性不足的群体，将通过各种教育项目融入爱荷华州州立大学的研究。此外，通过与艾姆斯中学科学教师的现有联系，PI计划向艾姆斯中学科学奥林匹克队的学生讲授压电器件并演示压电效应。

NON-TECHNICAL DESCRIPTION: Piezoelectric materials change their dimensions when subjected to electric fields, consequently their applications range from gas igniters, speakerphones, to medical ultrasonic imaging systems. In current commercial piezoelectric devices these materials contain ~60 wt.% of lead. Due to the toxicity of lead, recent legislation in many countries restricts its use. This project aims to uncover the fundamental mechanism of the piezoelectric deformation in lead-free ceramics. The research findings will ultimately lead to the production of ceramics that will replace lead-containing piezoelectric materials. Therefore, a significant impact on health and the environment is anticipated. In addition to getting graduate and undergraduate students from underrepresented groups involved, this project will also directly benefit the K-12 education in local schools in Ames, Iowa through the lectures on piezoelectric devices to the Science Olympiad (http://soinc.org/) team students. TECHNICAL DETAILS: The environmental concerns about lead in Pb(Zr1-xTix)O3 (PZT) have currently stimulated extensive worldwide researches on the development of lead-free piezoelectric ceramics. Previous researchers suggest that the two best systems, ceramics based on (K0.5Na0.5)NbO3 and those based on (Bi0.47Na0.47Ba0.06)TiO3, have completely different piezoelectric deformation mechanisms from those in PZT. Limited evidence indicates that the strain from the electric field-induced phase transition becomes significant. With the PI's unique in situ transmission electron microscopy technique, this project seeks to uncover the origin of the strain that develops under applied electric fields in these lead-free ceramics. Integrated with the experimental work, computational modeling based on density functional theory methods is also planned. The outcome of this project is expected to provide critical guidelines in the development of new lead-free compositions with high and yet temperature-stable piezoelectric properties. This project is designed to have a broad impact on graduate and undergraduate materials science education. Undergraduate students, especially those from underrepresented groups, will be integrated into research at Iowa State University through various educational programs. In addition, through existing connections with the Ames Middle School science teachers, the PI plans to give lectures on piezoelectric devices and demonstrate the piezoelectric effect to the Ames Middle School Science Olympiad team students.