CAREER: Elucidating the Formation and Evolution of Metastable Phases in Fluorite-Structured Ferroelectrics using Advanced Electron Microscopy

职业：使用先进电子显微镜阐明萤石结构铁电体中亚稳相的形成和演化

• 批准号: 2338558
• 负责人: Honggyu Kim
• 金额: $ 60.94万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-06-01 至 2029-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2338558&HistoricalAwards=false
• 关键词: CAREER; Elucidating; Formation; Evolution; Metastable

Non-Technical Summary: Ferroelectric materials are characterized by their ability to form local regions with spontaneous electric polarization (domains) that can be switched with an external electric field. This characteristic makes them attractive for information technologies such as memory and transistors. In particular, ferroelectric materials with a fluorite crystal structure are gaining prominence for next-generation memory and transistors. This is attributed to their superior scalability and compatibility with complementary metal-oxide-semiconductor processing, advantages not shared by conventional ferroelectric materials adopting a perovskite structure. However, as material dimensions shrink for high-density processing and devices integrate diverse materials, understanding and correlating domain structures with synthesis processes and ferroelectric performance pose challenges. This project, supported by the Ceramics Program in the Division of Materials Research, aims to address this challenge by developing novel characterization methods based on advanced electron microscopy techniques and in situ biasing experiments. This approach enables quantitative analysis of static and dynamic domain structures, producing reliable correlation of structural properties to ferroelectric switching characteristics. This, in turn, provides insights into new materials design principles for targeted ferroelectric performance. Aligned with the research, this Ceramics CAREER award supports the launch of a K-12 microscopy school for middle-school students from underrepresented schools in northern Florida. The goal of this outreach activity is to increase the participation of underrepresented students in the STEM workforce through hands-on activities in highly collaborative learning environments. In addition, this CAREER award facilitates the development of online learning modules on electron microscopy techniques and image processing methods by incorporating video tutorials and custom image analysis tools. These educational materials plan to be published and maintained on the PI group webpage and another open online platform (nanoHub.org), increasing accessibility and usability within the scientific community. Technical Summary: Harnessing thermodynamically metastable phases opens up new opportunities to control the properties of ceramic materials, thereby creating novel functionalities for real-world applications. However, identifying materials design pathways to stabilize targeted metastable materials poses challenges due to the difficulties in characterizing the structures of the ground-state and metastable phases and understanding their evolution under in-service conditions. To overcome this challenge and explore the science of controlling metastable ceramic materials, this CAREER award aims to characterize the mechanisms of the formation and evolution of metastable polar phases in nanoscale fluorite-structured ferroelectrics. Objectives include (i) developing high-precision phase indexing methods for identifying metastable polymorphs in hafnium oxide thin films, a model fluorite-structured ferroelectric material, (ii) establishing microstructure texturing for phase-pure nanoscale ferroelectric materials, (iii) building process-structure-property relationships by correlating structural and electrical properties, and (iv) elucidating polarization switching mechanisms using in situ biasing experiments. This project, supported by the Ceramics Program, employs scanning electron nanobeam diffraction and machine learning-aided image processing methods for unambiguous identification of metastable phases in ferroelectric thin films with quantitative structural information. Insights gained are expected to guide synthesis strategies for desirable metastable phases in ferroelectric thin films with controllable microstructure, expanding the materials design space for improved performance. The broader impact of this research includes the development of ceramic materials with technologically important functionalities arising from phase metastability or transition. Concurrently, this CAREER award supports education initiatives, including a K-12 microscopy school, online learning modules on electron microscopy for students at various levels, and research internship opportunities for underrepresented undergraduate students. The comprehensive education and outreach activities aim to increase awareness of cutting-edge ceramic materials research and prepare a diverse group of students for careers in STEM fields.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：铁电材料的特征是它们能够用自发的电动极化（域）形成本地区域，这些区域可以用外部电场切换。这种特征使它们对记忆和晶体管等信息技术具有吸引力。特别是，具有荧光岩晶体结构的铁电材料在下一代记忆和晶体管方面变得突出。这归因于它们的出色可伸缩性和与互补金属 - 氧化物 - 氧化型处理器的兼容性，这是采用钙钛矿结构的常规铁电材料所没有的优势。但是，随着材料的尺寸缩小了高密度处理和设备的缩小，将各种材料整合在一起，理解和将域结构与合成过程和铁电性性能构成挑战。该项目得到了材料研究部陶瓷计划的支持，旨在通过基于先进的电子显微镜技术和原位偏见实验来开发新颖的表征方法来应对这一挑战。这种方法可以对静态和动态域结构进行定量分析，从而产生结构特性与铁电交换特性的可靠相关性。反过来，这为目标铁电性能提供了新材料设计原理的见解。与研究一致，该陶瓷职业奖支持启动来自佛罗里达州北部代表性不足学校的中学学生的K-12显微镜学校。这项外展活动的目的是通过在高度协作的学习环境中动手活动来增加代表性不足的学生在STEM劳动力中的参与。此外，该职业奖通过合并视频教程和自定义图像分析工具，促进了电子显微镜技术和图像处理方法的在线学习模块的开发。这些教育材料计划将在PI组网页和另一个开放的在线平台（Nanohub.org）上发布和维护，从而增加了科学界的可访问性和可用性。技术摘要：利用热力学亚稳态阶段为控制陶瓷材料的特性提供了新的机会，从而为现实世界应用创造了新的功能。但是，识别材料的设计途径稳定目标的亚稳态材料会引起挑战，这是由于表征地基州和亚稳态阶段的结构的困难，并在服务内条件下了解了它们的演变。为了克服这一挑战并探索控制亚稳态陶瓷材料的科学，该职业奖的目的是表征纳米级荧光岩结构的铁电基质中亚稳态极相的形成和演变的机制。目的包括（i）开发高精度阶段索引方法，用于识别氧化物薄膜中的可稳态多晶型物，一种模型的荧光矿体结构的铁电材料，（ii）建立相位纳米级纳米级铁层次质量的微观结构质地，（III）建筑物结构及其式（III）的式（III），以及电源 - - 建筑物 - 建筑物的结构，以及电动性（III），以及电动性关系，以及（iii）的式（III），并且电动性关系，以及电动性（II I）使用原位偏见实验的切换机制。该项目在陶瓷计划的支持下，采用了扫描电子纳米骨衍射和机器学习辅助图像处理方法，用于在具有定量结构信息的铁电薄膜中明确鉴定亚稳态。预计获得的见解将指导具有可控微结构的铁电薄膜中理想的可稳态阶段的合成策略，从而扩大了材料设计空间以提高性能。这项研究的更广泛的影响包括开发具有相稳定性或过渡性引起的技术重要功能的陶瓷材料。同时，该职业奖支持教育计划，包括K-12显微镜学校，在线学习模块，用于各个级别的学生电子显微镜，以及为代表性不足的本科生提供的研究实习机会。全面的教育和外展活动旨在提高人们对尖端陶瓷材料研究的认识，并为STEM领域的职业生涯做好准备。该奖项反映了NSF的法定任务，并认为值得通过基金会的知识分子的智力优点和更广泛的影响来通过评估来提供支持。