Domain Boundary - Grain Boundary Interactions in Ferroelectrics

非技术描述：铁电材料（具有自发极化，可以通过施加电场重新定向-铁磁材料的电学模拟）包括数十亿美元的产业;几乎在每种情况下，功能特性都取决于畴壁（具有不同极化方向的区域之间的边界）的移动性。该项目正在量化现实微观结构对这些畴壁的移动性的作用，并将这些结果广泛传播给科学界和工业界。在研究生一级，该项目正在培养将成为下一代科学和技术领导者的学生。毕业生通常会在高科技公司或大学教师中找到工作。此外，首席研究员将完成教科书的第二版，材料工程：键合，结构和结构-性能关系。技术专长：与钉扎畴壁和铁电材料中的相边界运动的基本过程和长度尺度目前了解甚少的一般情况下。该项目是使用电气和机电表征，透射X射线显微镜，纳米探针X射线散射，和piezoresponse力显微镜的组合，以开发一个定量数据库的方式，不同的机械边界条件，包括薄膜应力，晶界取向差角，和相互作用的晶体缺陷影响相关运动的域壁。来自宾夕法尼亚州立大学、阿贡国家实验室和丹麦技术大学的跨学科研究人员团队正在制备和表征具有各种不同晶界角的模型样品，以便直接测量Pb（Zr，Ti）O3薄膜中畴壁相关运动的长度尺度。的功能特性被映射通过瑞利和Preisach方法的组合。通过压电响应力显微镜进行的局部测量对大面积测量进行了补充，以绘制团簇的大小，其中存在不同应变状态和晶界取向差的畴壁集体运动。在场激发下用纳米探针衍射测量来询问样品。此外，被确定为强或弱响应的区域中的局部域结构正在通过X射线暗场显微镜进行询问，以便在空间上映射缺陷/域壁相互作用。本地化的主要钉扎位点，然后在结构上探测这些地区的非破坏性，同时激发样品电允许阐明局部扰动的集体运动的功能域壁的影响的可能性。这些结果使得铁电薄膜、陶瓷和单晶的模型得以开发，从而更准确地捕捉基本的材料物理学。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: Ferroelectric materials (which have a spontaneous polarization which can be reoriented by an applied electric field – the electrical analog of ferromagnetic materials) comprise a multi-billion-dollar industry; in nearly every case, the functional properties depend on the mobility of domain walls (the boundaries between regions with different polarization directions). This project is quantifying the role of realistic microstructure on the mobility of these domain walls, and broadly disseminating these results to the scientific community and industry. At the graduate level, the project is training students who will become next-generation scientific and technology leaders. Graduates typically find employment either at high-tech companies or as university faculty members. In addition, the principal investigator will complete a second edition of the textbook, Materials Engineering: Bonding, Structure, and Structure-Property Relationships.TECHNICAL DETAILS: The fundamental processes and length scales associated with pinning domain wall and phase boundary motion in ferroelectric materials are at present poorly understood for general cases. This project is using a combination of electrical and electromechanical characterization, transmission X-ray microscopy, nanoprobe X-ray scattering, and piezoresponse force microscopy to develop a quantitative database on the way that different mechanical boundary conditions, including film stress, grain boundary misorientation angle, and interacting crystallographic defects influence correlated motion of domain walls. The interdisciplinary team of researchers from Penn State, Argonne National Laboratories and the Technical University of Denmark are preparing and characterizing model samples with a wide range of different grain boundary angles in order to directly measure the length scales over which correlated motion of domain walls occurs in Pb(Zr,Ti)O3 thin films. The functional properties are being mapped through a combination of Rayleigh and Preisach approaches. Large area measurements are being complemented with local measurements via piezoresponse force microscopy to map the size of the clusters where there is collective motion of domain walls for different strain states and grain boundary misorientations. Samples are being interrogated with nanoprobe diffraction measurements under field excitation. Moreover, the local domain structure in regions identified as strongly or weakly responsive are being interrogated via X-ray dark field microscopy in order to spatially map the defect/domain wall interactions. The ability to localize the major pinning sites and then structurally probe those regions non-destructively while exciting the sample electrically allows the possibility of elucidating the impact of local perturbations on the collective motion of functional domain walls. These results are allowing models of ferroelectric films, ceramics, and single crystals to be developed to capture the fundamental material physics more accurately.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.