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.

非技术摘要铁电 (FE) 材料表现出可通过电场切换的自发极化。这些材料由域（极化方向相同的区域）组成。有限元材料已用于各种电子设备，例如红外传感器、执行器和超声波换能器。虽然众所周知，域配置的修改可以增强有限元材料的机电和介电性能，但对于什么是理想的域尺寸或域壁密度（即相邻域之间的边界区域）存在知识差距。优化宏观材料性能。该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 可以在介观长度（1 至数十微米）内研究材料原子结构在几毫秒至数百秒的时间内的动力学。这个范围对于解释原子现象对宏观行为的影响至关重要，而当前的现有技术（例如 X 射线衍射和压响应力显微镜）无法有效地实现这一范围。新提出的方法比较了施加电场下 X 射线图像的位移。将对偏移程度进行统计分析，以揭示材料中机电响应的机制，包括通过连续域变形或离散域壁运动。这项研究的结果将证明上述方法的可行性，以进一步研究畴壁密度和畴尺寸对有限元材料性能的影响。此外，该提案还包括旨在促进代表性不足的少数群体 (URM) 中 STEM 职业的教育计划。这些计划涉及 K-12 推广计划、为大学生整合 STEM 课程，以及为 URM 小组的高中生和大学生提供研究指导。 技术摘要 拟议的研究旨在通过证明研究铁电 (FE) 领域工程背后的基本机制概念研究区分与机电的内在（即域扩展和偶极子旋转）和外在（即离散域壁运动）贡献相关的 X 射线散射行为（即压电）响应。 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，这是解释原子现象效应的临界长度尺度宏观材料行为。相比之下，基于 X 射线衍射的现有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域切换。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域配置。同样，虽然压响应力显微镜可以可视化有限元域图案，但由于扫描速度的限制，很难表征介观尺度的动态原子结构变化。相比之下，XPCS 获取帧中的散射信号，以在几毫秒到数百秒的时间内跟踪所有位置的图案移位。该项目将使用 Pb(Mg1/3Nb2/3)O3-PbTiO3 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。目标是开发一种“双场”XPCS 方法和统计分析工具，用于评估内在和外在机制对压电和介电性能的贡献。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。研究成果还将用于通过各种举措，例如外展活动和创新课程工作，来教育来自代表性不足的少数群体的 K-12、本科生和研究生水平的学生。该奖项反映了 NSF 的法定使命，并被认为是值得的通过使用基金会的智力优势和更广泛的影响审查标准进行评估来获得支持。