In-situ and ex-situ STEM study of non-conventional line defects in perovskite oxides

钙钛矿氧化物中非常规线缺陷的原位和异位 STEM 研究

• 批准号: 2309431
• 负责人: Andre Mkhoyan
• 金额: $ 49.59万
• 依托单位: University of Minnesota-Twin Cities
• 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 2027-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2309431&HistoricalAwards=false
• 关键词: situ; ex; STEM; study; non

Non-Technical Summary The nanoscale materials present in electronic devices used every day should be engineered to make the devices smaller and increase their functions. To do this, new ways to harvest the properties of these materials should be found. One route is engineering atomic-level defects naturally present in these nanomaterials. While all crystalline nanomaterials have variety of defects in them, some defects are more promising than others. One dimensional defects, often referred to as line defects, are only a-few-atoms-wide and run along the entire crystal. This is an excellent opportunity to engineer them to get the properties wanted. Since they are only a-few-atoms-wide, they are intriguing objects embedded inside the main material, and they can have new and exciting properties that are unique to them. Study of these line defects requires ultra-high-resolution microscopes with features that can probe the properties of these defects. This project employs specialized analytical scanning transmission electron microscopes to study the identities, properties, and origins of these line defects. Combining these observations with theoretical predictions will provide additional flexibility when characterizing the defects. Perovskite oxide thin films have proven to be excellent hosts for such defects. The results will affect not only the science of defects in perovskite crystals, but also affect next-generation nanomaterial engineering by defect engineering. Within the framework of this project, high-school students will visit the University of Minnesota to have interactive tours of the Electron Microscopy Center at the Characterization Facility and see high-resolution electron microscopes in action. This outreach educational activity will be an academic-year-long program. Each year, groups of students and teachers from local high schools will participate in these tours, including schools with a considerable minority student population. Such a real-time dive into the structure of the materials and the operations of advanced electron microscopes should inspire students to pursue technical disciplines in college. It should also help teachers better convey to their students the science behind nanomaterials and microscopes using images obtained during their University of Minnesota visit. Technical SummaryAdvances over the past two decades have shown large numbers of materials can be scientifically exciting and technologically desirable when they have dimensions at the nanometer scale. Discoveries of new phenomena unique to nanoscale materials are being made almost daily, ranging from new physics—such as quantum transport of qubits in semiconductor nanowires or tetradymite chalcogenides being topological insulators—to new applications. Identifying the next frontiers in nanomaterials becomes more-and-more relevant. A new path for exciting new science and next-generation technology is possible through exploring and engineering the naturally-occurring defects in nanoscale materials, especially extended defects. These extended line (or 1D, dislocations and disclination, etc.) and planar (or 2D, grain boundaries, stacking faults, etc.) defects are particularly promising because they run across the entire crystal in one or two directions and are atomically small in other directions. Among them, line defects are only a-few-atoms-wide in two directions and extended in the third direction. With such natural geometry, it is expected that the properties of 1D defects should resemble a chain of atoms or a chain of single-unit cells. These defects should be rich with new physics and new quantum materials’ phenomena not seen in 2D materials. Nanostructures containing them could take advantage of both the features of the defect and the host. The study of new defects – understanding their properties and engineering them into new structures – is the main topic of this project, and it could be what is next in nanomaterials. Determining the effects of key factors (such as composition, strain, and temperature) on formation of line defects and their rearrangements in perovskite oxides are central aims of this work. Perovskite oxides (ABO3), are highly flexible and can accommodate various types of distortions, due to their complex structure. Such structural flexibility allows the perovskite host to accommodate unique extended defects, including those of different compositions. Thus, exploring such non-conventional defects in perovskite oxides has the potential to be extremely fruitful, largely expand the fundamental science of ceramic crystals, and transform next-generation nanomaterials. This study of non-conventional 1D line defects in perovskite oxides will be conducted ex-situ and in-situ using atomic-resolution, analytical scanning transmission electron microscopy (STEM) aided by density function tehroy (DFT) calculations.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 日常使用的电子设备中存在的纳米级材料应该被设计成使设备更小并增强其功能。为此，应该找到利用这些材料特性的新方法。虽然所有晶体纳米材料都存在多种缺陷，但有些缺陷比其他缺陷更有前景，通常称为线缺陷，只有几个原子宽并沿着该缺陷延伸。整个晶体。这是对它们进行改造以获得所需特性的绝佳机会，因为它们只有几个原子宽，所以它们是嵌入在主要材料中的有趣物体，并且它们可以具有独特的新的、令人兴奋的特性。研究这些线缺陷需要具有能够探测这些缺陷特性的超高分辨率显微镜，该项目采用专门的分析扫描透射电子显微镜，结合这些观察结果来研究这些线缺陷的特性、特性和起源。理论预测将在表征时提供额外的灵活性钙钛矿氧化物薄膜已被证明是此类缺陷的绝佳宿主，这些结果不仅会影响钙钛矿晶体缺陷的科学，而且还会影响该项目框架内的下一代纳米材料工程。高中生将参观明尼苏达大学的电子显微镜中心的表征设施，并观看高分辨率电子显微镜的运行情况。这项外展教育活动将每年持续一学年。团体来自当地高中的学生和教师将参加这些参观，其中包括有相当多少数族裔学生的学校，这种实时深入了解材料结构和先进电子显微镜操作的方式应该会激励学生学习技术学科。它还可以帮助教师使用在明尼苏达大学访问期间获得的图像更好地向学生传达纳米材料和显微镜背后的科学知识。具有纳米级的尺寸。纳米级材料特有的新现象几乎每天都在被发现，从新物理学（例如半导体纳米线中的量子传输或作为拓扑绝缘体的辉辉石硫属化物）到确定纳米材料的下一个前沿领域越来越多。通过探索和设计纳米级材料中自然发生的缺陷，特别是这些延伸的缺陷（或一维，位错和向错等）和平面（或二维、晶界、堆垛层错等）缺陷特别有前途，因为它们在一个或两个方向上贯穿整个晶体，而在其他方向上是原子级的。缺陷在两个方向上只有几个原子宽，并在第三方向上延伸，预计一维缺陷的特性应该类似于原子链或单晶胞链。缺陷应该是富含二维材料中未见的新物理和新量子材料现象，可以利用缺陷和主体的特征，对新缺陷的研究——了解它们的特性并将其设计成新的结构。确定关键因素（例如成分、应变和温度）对钙钛矿氧化物中线缺陷形成及其重排的影响是该项目的主要主题，并且可能是纳米材料的下一步发展。 。钙钛矿氧化物（ABO3）具有高度的灵活性，由于其复杂的结构，可以适应各种类型的变形，这种结构灵活性使钙钛矿主体能够适应独特的扩展缺陷，包括不同成分的缺陷，因此，探索这种非常规缺陷。钙钛矿氧化物中的非常规一维线缺陷的研究有可能取得丰硕成果，极大地扩展陶瓷晶体的基础科学，并改变下一代纳米材料。将使用原子分辨率、分析型扫描透射电子显微镜 (STEM) 并辅以密度函数法 (DFT) 计算对氧化物进行异位和原位分析。该奖项反映了 NSF 的法定使命，并通过使用以下方法进行评估，认为值得支持：基金会的智力价值和更广泛的影响审查标准。