Investigation of the ferroelectric domain dynamics and its effects on macroscopic behaviors using a synchrotron X-ray photon correlation spectroscopy

使用同步加速器 X 射线光子相关光谱研究铁电畴动力学及其对宏观行为的影响

• 批准号: 2309184
• 负责人: Jong Ryu
• 金额: $ 18万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2309184&HistoricalAwards=false
• 关键词: Investigation; ferroelectric; domain; dynamics; its

NON-TECHNICAL SUMMARYFerroelectric (FE) materials show spontaneous polarization that can be switched by an electric field. These materials consist of domains, the regions where the polarization is oriented in the same directions. FE materials have been used in various electronic devices such as infrared sensors, actuators, and ultrasound transducers. While it is well recognized that the modification of the domain configurations can enhance the electromechanical and dielectric properties of the FE materials, there is a knowledge gap regarding what is the ideal domain size or domain wall density (i.e., boundary regions between adjacent domains) to optimize the macroscopic material properties. The proposed research aims to develop an in-situ characterization method based on the X-ray photon correlation spectroscopy (XPCS). XPCS can investigate the dynamics of the atomic structures of materials over a range of time from milliseconds to hundreds of seconds in the mesoscale length (1 to tens of micrometers). This range is a critical to explaining the effect of atomistic phenomena on the macroscopic behavior and not efficiently accessible by the current existing techniques, such as X-ray diffraction and piezoresponse force microscopy. The newly proposed method compares the shift of X-ray images under applied electric field. The degree of shift will be statistically analyzed to reveal the mechanisms for electromechanical response in the material, including through continuous domain deformation or discrete domain wall motion. The outcome of this research will be a proof-of-concept of the viability of the above approach for further investigations of the effects of domain wall density and domain size on the FE material properties. Additionally, this proposal includes educational plans aimed at promoting STEM careers among underrepresented minority (URM) groups. These plans involve K-12 outreach initiatives, integrating STEM curriculum for university students, and providing research mentorship to high school and college students from URM groups.TECHNICAL SUMMARYThe proposed research aims to investigate the fundamental mechanisms behind the ferroelectric (FE) domain engineering through proof-of-concept research distinguishing X-ray scattering behaviors associated with the intrinsic (i.e., domain extension and dipole rotation) and extrinsic (i.e., discrete domain wall motion) contributions to the electromechanical (i.e., piezoelectric) response. The proposed approach by X-ray photon correlation spectroscopy (XPCS) provides a fundamentally new method to investigate the domain and domain wall effects in the mesoscopic (one to tens of microns) range, which is a critical length scale explaining the effect of atomistic phenomena on the macroscopic material behavior. For comparison, the existing techniques based on X-ray diffraction can estimate domain switching on a macroscopic scale, by using the relative intensity of the corresponding diffraction peak. Furthermore, the theoretical estimation is limited to the domain configuration that can be perfectly described by the diffraction peaks used in the calculation. Similarly, while piezoresponse force microscopy can visualize FE domain patterns, it is difficult to characterize the dynamic atomic structure changes at the mesoscale, due to the scanning speed limitations. In contrast, XPCS acquires the scattering signals in a frame to track the pattern shift in all locations over milliseconds to hundreds of seconds. This project will use Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals to test if the statistical distributions of the XPCS decorrelation functions can distinguish between the effects of intrinsic and extrinsic responses. The goal is to develop a 'two-field' XPCS method and a statistical analysis tool for assessing the contributions of intrinsic and extrinsic mechanisms to the piezoelectric and dielectric properties. This project also aims to educate the next generation of engineers and scientists through multidisciplinary research involving materials science, X-ray characterization, and data science. The research outcome will be also used to educate K-12, undergraduate, as well as graduate-level students from underrepresented minority groups through various initiatives, such as outreach activities and innovative curricular efforts.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.

非技术概述铁电（FE）材料显示出可以通过电场切换的自发极化。这些材料由畴组成，畴是极化方向相同的区域。FE材料已用于各种电子设备，如红外传感器、致动器和超声换能器。虽然很好地认识到，域配置的修改可以增强FE材料的机电和介电性质，但是关于什么是理想的域尺寸或域壁密度（即，相邻区域之间的边界区域）以优化宏观材料性能。提出的研究旨在开发一种基于X射线光子相关光谱（XPCS）的原位表征方法。XPCS可以在中尺度长度（1至数十微米）上研究从毫秒到数百秒的时间范围内材料原子结构的动态。这个范围对于解释原子现象对宏观行为的影响至关重要，并且目前现有的技术（如X射线衍射和压电响应力显微镜）无法有效地访问。新提出的方法比较了X射线图像在外加电场下的位移。将对偏移程度进行统计分析，以揭示材料中的机电响应机制，包括通过连续畴变形或离散畴壁运动。这项研究的结果将是一个概念验证的可行性，上述方法为进一步调查的影响域壁密度和域大小的FE材料性能。此外，该提案还包括旨在促进代表性不足的少数民族（URM）群体的STEM职业的教育计划。这些计划涉及K-12外展计划，为大学生整合STEM课程，并为来自URM团体的高中和大学生提供研究指导。技术概述拟议的研究旨在通过概念验证研究来研究铁电（FE）域工程背后的基本机制，区分与固有（即，畴扩展和偶极旋转）和非本征（即，离散畴壁运动）对机电（即，压电）响应。通过X射线光子相关光谱（XPCS）提出的方法提供了一种全新的方法来研究介观（一到几十微米）范围内的畴和畴壁效应，介观范围是解释原子现象对宏观材料行为影响的临界长度尺度。相比之下，现有的基于X射线衍射的技术可以通过使用相应衍射峰的相对强度来估计宏观尺度上的畴切换。此外，理论估计仅限于计算中使用的衍射峰可以完美描述的畴配置。同样，虽然piezoresponse力显微镜可以可视化FE域模式，它是很难表征的动态原子结构的变化在介观尺度，由于扫描速度的限制。相比之下，XPCS在一帧中获取散射信号，以跟踪所有位置的模式偏移，时间从毫秒到数百秒不等。本项目将使用Pb（Mg 1/3 Nb 2/3）O3-PbTiO 3单晶来测试XPCS去相关函数的统计分布是否可以区分内在和外在响应的影响。我们的目标是开发一个“双场”XPCS方法和统计分析工具，用于评估的贡献的内在和外在的机制的压电和介电性能。该项目还旨在通过涉及材料科学，X射线表征和数据科学的多学科研究来教育下一代工程师和科学家。研究成果也将用于教育K-12，本科生，以及研究生水平的学生，从代表性不足的少数群体通过各种举措，如外展活动和创新的课程努力。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。