Restricting Ferroelectric Domain Wall Motion with Volume Defects--Nanoprecipitates

用体积缺陷限制铁电畴壁运动——纳米沉淀

• 批准号: 2110264
• 负责人: Xiaoli Tan
• 金额: $ 56.95万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2110264&HistoricalAwards=false
• 关键词: Restricting; Ferroelectric; Domain; Wall; Motion

NON-TECHNICAL DESCRIPTION: Piezoelectric ceramics are functional materials that develop electric charges when subjected to mechanical forces and change their dimensions when subjected to electric fields. Such conversion of energies between mechanical and electric forms can have extremely high efficiency (up to 90%); and hence, these ceramics have widespread applications in critical technologies such as SONAR, medical imaging, and non-destructive evaluation. Currently, the technique to manipulate and improve their functional properties is to introduce impurity atoms in the ceramic. However, this technique has reached its fundamental limit. The current project explores a radically new mechanism -- introducing highly dispersed impurity nanocrystals (~50 nm) into the bulk ceramic -- to further improve the performance of piezoelectric ceramics and allow them to function at higher temperatures and under higher electric fields. These improved ceramics can then be used to create next generation high-power devices that operate under more extreme conditions. In addition to technical contributions, this project also provides learning and career advancement opportunities for many communities. Both graduate and undergraduate students, many of whom from underrepresented groups, are involved in this project; graduates who study ceramics science can typically find employment in national labs and industry sectors of microelectronics and manufacturing; and various demonstrations on piezoelectric technologies are given to K-12 students to encourage scientific thinking and spark interest in science and engineering fields. TECHNICAL DETAILS: This project aims to establish a novel mechanism of stabilizing the domain structure and hardening piezoelectric ceramics with nanoscale coherent precipitates. Compared to the state-of-the-art point-defect technique, volume defects provide stronger restrictions and are stable under higher temperatures. Therefore, this project helps realize high-power piezoelectric transducers that can be used at higher driving frequencies and vibration velocities. As a model system, this project focuses on lead-free BaTiO3/CaTiO3 compositions, where slanted solvus lines in the phase diagram guide the precipitation of uniformly dispersed nanoscale coherent crystals in bulk polycrystalline ceramics. Presumably, the CaTiO3-rich precipitate remains non-polar when it is larger than a critical size and becomes polar when it is below the critical size. The ferroelectric domain wall in the BaTiO3-rich matrix is hypothesized to be restricted in different modes by precipitates of different sizes. The hypotheses are directly verified using the in-situ heating and biasing, and other advanced transmission electron microscopy techniques. Both graduate and undergraduate students are involved in this project and are trained with ceramic manufacturing and property characterization. The doctoral student is further trained with cutting-edge transmission electron microscopy techniques, which are used to characterize precipitate/matrix interfaces at the atomic level in terms of chemistry, displacement, strain, and charge.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.

非技术描述：压电陶瓷是功能材料，在受到机械力时会产生电荷并在受到电场时改变其尺寸。机械和电形式之间能量的这种转化可以具有极高的效率（高达90％）；因此，这些陶瓷在诸如声纳，医学成像和非破坏性评估等关键技术中具有广泛的应用。当前，操纵和改善其功能特性的技术是在陶瓷中引入杂质原子。但是，该技术已达到其基本限制。当前的项目探索了一种彻底的新机制 - 将高度分散的杂质纳米晶体（〜50 nm）引入散装陶瓷 - 以进一步提高压电陶瓷的性能，并允许它们在较高的温度和较高的电场下运行。然后，这些改进的陶瓷可用于创建在更极端条件下运行的下一代高功率设备。除技术贡献外，该项目还为许多社区提供了学习和职业发展机会。研究生和本科生，其中许多人来自代表性不足的团体，都参与了该项目；研究陶瓷科学的毕业生通常可以在微电子和制造业的国家实验室和行业领域找到就业。 K-12学生提供了有关压电技术的各种演示，以鼓励科学思维并引起对科学和工程领域的兴趣。技术细节：该项目旨在建立一种稳定域结构和用纳米级相干沉淀的新型机制。与最新的点缺陷技术相比，体积缺陷提供了更强的限制，并且在较高的温度下是稳定的。因此，该项目有助于实现可在较高驱动频率和振动速度下使用的高功率压电传感器。作为模型系统，该项目着重于无铅BATIO3/CATIO3组合物，在相图中，倾斜的溶剂线指导在散装多晶陶瓷中均匀分散的纳米级相干晶体的沉淀。据推测，当它大于临界大小时，富含CATIO3的沉淀物在临界大小以下时会变得非极性。假设富含Batio3的基质中的铁电域壁被不同尺寸的沉淀物限制在不同模式下。使用原位加热和偏置以及其他先进的透射电子显微镜技术直接验证了这些假设。研究生和本科生都参与了该项目，并接受了陶瓷制造和财产特征的培训。该博士学生接受了尖端的传输电子显微镜技术的进一步培训，该技术用于在原子水平上以化学，流离失所，应变和费用来表征原子水平的沉淀/基质接口。该奖项反映了NSF的法定任务，并认为通过基金会的知识优点和广泛的criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia rection the奖项都值得通过评估。

项目成果

Coherent Precipitates with Strong Domain Wall Pinning in Alkaline Niobate Ferroelectrics

• DOI: 10.1002/adma.202202379
• 发表时间: 2022-08
• 期刊: Advanced Materials
• 影响因子: 29.4
• 作者: Changhao Zhao;Shuang Gao;H. Kleebe;X. Tan;J. Koruza;J. Rödel