Materials World Network: Gradient-Enabled Ferroic Phenomena: Tunable Metastable States, Roto-Flexo, and Transport Properties

材料世界网络：梯度启用的铁性现象：可调亚稳态、Roto-Flexo 和传输特性

• 批准号: 1210588
• 负责人: Venkatraman Gopalan
• 金额: $ 45万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1210588&HistoricalAwards=false
• 关键词: Materials; World; Network; Gradient; Enabled

TECHNICAL SUMMARY: The functional properties of ferroelectrics and ferroelastics, materials with built-in polarization and elastic distortion states in their crystal structure, respectively, are typically reliant on their response under uniform spatial elastic and electric fields, e.g., switching, piezoelectric, and electro-optic responses. There is also a rich range of ferroic phenomena arising under gradient fields, which receive much less attention. This project is based on two new discoveries/ideas initiated by the US/Ukraine team: New highly tunable metastable states and roto-flexo phenomena. Strong gradient fields created at and in the proximity of domain walls can result in local phase transitions that lead to new bulk polar phases not normally expected in classic textbook ferroelectrics, and even in non-polar ferroelastics. In all oxide interfaces with oxygen octahedral tilts, the creation of a polarization (up to 1-10 microC/cm2) is predicted through a rotostriction-flexoelectric product effect that can significantly impact the interface charge transport. Using optical second harmonic generation microscopy, Raman microscopy, scanning probe microscopy, nanoscale X-ray diffraction imaging, z-contrast scanning transmission electron microscopy, analytical theory, phase-field modeling, and first principles theory, this collaborative team explores these new phenomena. Broadly speaking, the US team (Pennsylvania State University, Oak Ridge National Labs, Argonne National Labs) conducts experimental research and performs phase-field simulations, and the Ukrainian team (National Academy of Sciences, Ukraine) focuses on developing the theoretical framework. NON-TECHNICAL SUMMARY: This project can potentially lead to new highly tunable, large piezoelectric response lead-free materials useful for precision motion and sensors. Gradient couplings at interfaces can lead to two-dimensional electron gas systems of great current interest for next generation high-speed transistors. This project also develops cutting-edge quantitative microscopy tools and advances theoretical modeling by simulating flexoelectric and other gradient effects. The NSF award provides funds to energize and sustain an international research team, which started in 2007. It funds undergraduate and graduate students to work and collaborate in a global context, supports extended visits across the Atlantic by PIs and students, furthers interactions between a university (Penn State), national labs (Oak Ridge and Argonne) and international collaborators (NAS-Ukraine), supports outreach activities through K-12, and provides research opportunities for women and underrepresented groups.This project is supported by the Electronic and Photonic Materials program and Office of Special Programs, Division of Materials Research.

技术摘要：铁电和铁塑料的功能特性，其晶体结构中具有内置极化和弹性失真状态的材料通常依赖于它们在均匀的空间弹性和电场下的响应，例如开关，压电，压电和电响应响应。在梯度领域下还产生了丰富的铁族现象，这些现象受到较少的关注。该项目基于美国/乌克兰团队发起的两个新发现/想法：新型高度可调的亚稳态状态和Roto-Flexo现象。在域壁的邻近和近端创建的强梯度场可能会导致局部相变，从而导致通常在经典教科书铁电信甚至非极性铁启示中期望的新散装极相位。在所有具有氧气八人体倾斜的氧化物界面中，通过旋转式曲线 - 柔性电主产物效应预测极化（最高1-10微克/cm2）的产生，从而可以显着影响界面电荷传输。使用光学第二谐波生成显微镜，拉曼显微镜，扫描探针显微镜，纳米级X射线衍射成像，z对比度扫描透射电子显微镜，分析理论，相位场建模和第一原理理论，该协作团队探索了这些新现象。从广义上讲，美国团队（宾夕法尼亚州立大学，橡树岭国家实验室，阿尔贡国家实验室）进行了实验研究并进行了相位模拟，而乌克兰团队（乌克兰国家科学院，乌克兰）专注于开发理论框架。非技术摘要：该项目可能会导致新的高度可调的大型压电响应无铅的无铅材料，可用于精确运动和传感器。接口处的梯度耦合可以导致下一代高速晶体管具有极大兴趣的二维电子气体系统。该项目还开发了尖端的定量显微镜工具，并通过模拟挠性和其他梯度效应来进步理论建模。 The NSF award provides funds to energize and sustain an international research team, which started in 2007. It funds undergraduate and graduate students to work and collaborate in a global context, supports extended visits across the Atlantic by PIs and students, furthers interactions between a university (Penn State), national labs (Oak Ridge and Argonne) and international collaborators (NAS-Ukraine), supports outreach activities through K-12, and provides research妇女和代表性不足的群体的机会。该项目得到了电子和光子材料计划以及材料研究部特别计划办公室的支持。