Materials World Network: Nanoscale Structure-Property Relationships in Lead Free Morphotropic Phase Boundary Piezoelectrics

这是弗吉尼亚理工大学和里海大学（美国团队成员）以及华威大学（英国）、牛津大学（英国）、诺夫哥罗德州立大学（俄罗斯）和上海陶瓷研究所（中国）的国际合作伙伴的联合项目。本研究通过系统地研究局域和晶体结构及其对性能的影响，探讨了无铅系统中压电响应的控制机制。(Na1/2Bi1/2) TiO3 ?采用成分接近形态营养相边界（MPB）的BaTiO3 （NBT-BT）单晶作为无铅体系的代表。研究了纳米级畴结构及其铁电响应作为电场、压力和温度的函数，以确定MPB区域的相变序列，并确定中间桥接相的存在。该研究面临的另一个具有挑战性的问题是无铅材料中畴工程机理的阐述。利用衍射和光谱学技术对无铅晶体的局部纳米结构和微观结构进行了研究，描述了无铅晶体的对称关系、偶极矩的性质、长程平均晶体结构、原子中的有序/无序。S局部环境，以及极化方向。这些研究使人们能够理解纳米和宏观长度尺度上的结构-性能关系，并用于识别无铅和铅基体系中MPBs的异同。通过在同行评议的期刊上联合发表文章、建立无铅材料网站和组织关于铅的专题讨论会，广泛传播所取得的成果。在未来的年度科学会议上免费使用压电材料。A我们？英国，美国？实施俄罗斯、美国和中国学生交流计划，使从事该项目的研究生接触到国际研究环境。在这项工作的第二年，将推出一个网站，发布所有的发展、成就、出版物和幻灯片演示。蒙哥马利县学校（弗吉尼亚州布莱克斯堡）将启动一个试点教育项目，重点是将无铅压电致动器和传感器纳入他们的机器人项目。该奖项由NSF国际科学与工程办公室（OISE）和MPS多学科活动办公室（OMA）共同资助。

This is a joint project between Virginia Tech and Lehigh University (US team members) and international partners consisting of the University of Warwick (UK), the University of Oxford (UK), Novgorod State University (Russia), and the Shanghai Institute of Ceramics (China). The research addresses the mechanisms controlling the piezoelectric response in lead free systems by systematically studying the local domain and crystal structure and their effect on properties. (Na1/2Bi1/2)TiO3?BaTiO3 (NBT-BT) single crystals of compositions close to morphotrophic phase boundary (MPB) are used as the representative lead free system. The nanoscale domain structure and its ferroelectric response are studied as a function of electric field, pressure and temperature to identify the phase transformational sequences in the MPB region and to determine the presence of intermediate bridging phases. Another challenging issue confronted in this research is formulation of the mechanism of domain engineering in the lead free materials. Both the local nano-structure and the microstructure of the lead-free crystals is studied using diffraction and spectroscopic techniques to delineate the symmetry relations, nature of the dipole moment, long-range average crystal structure, order/disorder in the atom?s local environment, and orientation of polarization.These studies enable the understanding of the structure-property relations on the nano- and macro- length scales and are used to identify similarities and differences between MPBs in lead-free and lead-based systems. Wide dissemination of the results obtained is done through joint publications in peer-reviewed journals, by developing a website on lead free materials, and by organizing the symposia on lead ? free piezoelectrics at future annual scientific meetings. A US ? UK, US ? Russia, and US-China student exchange program is implemented to expose the graduate students working on the project to an international research environment. A website will be launched in the second year of this effort posting all the developments, achievements, publications, and power point presentations. A pilot education program will be initiated with Montgomery County School (Blacksburg, VA), with focus on incorporating lead-free piezo-actuators and sensors into their robotics program.This award is co-funded by the NSF Office of International Science and Engineering (OISE) and the MPS Office of Multidisciplinary Activities (OMA).