Nanocrystal Surface and Interfacial Free Energies on Vicinal Surfaces

邻近表面上的纳米晶体表面和界面自由能

• 批准号: 1410596
• 负责人: Jian-Min Zuo
• 金额: $ 42万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1410596&HistoricalAwards=false
• 关键词: Nanocrystal; Surface; Interfacial; Free; Energies

NON-TECHNICAL SUMMARY: This research focuses on the fundamental challenge in the study of nanostructured materials: how to determine their interfacial structure and their thermodynamic properties. A combined synthesis, characterization and modeling effort is proposed to address this challenge. Surface and interfacial properties will be measured and computed for supported nanoparticles and correlated with structure. Results are expected to have a direct impact on materials that are critical to substantial parts of technology, major components of the chemical industry, and exciting new developments in medical diagnostics. The research will be integrated with outreach efforts, including high school visits and undergraduate education. Results from this research project will be incorporated in the web-based educational materials for teaching students about structure and diffraction, infrastructure for which is already in place (see http://emaps.mrl.uiuc.edu/ or google webemaps). This particular website is now listed as one of the best web resources for learning electron diffraction.TECHNICAL SUMMARY: A combined experimental and theoretical study is proposed for the determination of surface and interface energies and correlation with atomic structure. Epitaxial Au nanocrystals supported on oxides will be synthesized using techniques developed in the PI's group. Aberration corrected scanning transmission electron microscopy (STEM) and transmission electron microscopy (TEM) will be used to characterize the equilibrium shapes of Au nanocrystals and as well as their interfacial structure. The structural data will be used to compute interface and step energies from first principles, which will be compared with experimental measurements based on the equilibrium shapes of supported nanocrystals. The experimental part takes the advantage of recent developments in electron microscopy, which promise imaging of oxygen atoms at the interface as well as 3D imaging of interfacial structure by depth sectioning. For theory, an energy density method will be used to compute energy distribution at surfaces and interfaces. The program builds upon the progress that has been made on Au nanocrystals supported on flat rutile (110) surfaces, and extends the study to vicinal surfaces to enable a measurement of step energies.

非技术摘要：本研究重点关注纳米结构材料研究中的基本挑战：如何确定其界面结构及其热力学性质。提出了综合综合、表征和建模工作来应对这一挑战。将测量和计算支持的纳米颗粒的表面和界面特性，并将其与结构相关联。研究结果预计将对技术的重要部分、化学工业的主要组成部分以及医疗诊断领域令人兴奋的新发展至关重要的材料产生直接影响。该研究将与推广工作相结合，包括高中访问和本科教育。该研究项目的结果将被纳入基于网络的教育材料中，用于向学生讲授结构和衍射，其基础设施已经就位（参见http://emaps.mrl.uiuc.edu/或google webemaps）。这个特定的网站现已被列为学习电子衍射的最佳网络资源之一。技术摘要：提出了一种实验和理论相结合的研究来确定表面和界面能量以及与原子结构的相关性。氧化物支撑的外延金纳米晶体将使用 PI 小组开发的技术来合成。像差校正扫描透射电子显微镜 (STEM) 和透射电子显微镜 (TEM) 将用于表征金纳米晶体的平衡形状及其界面结构。 结构数据将用于根据第一原理计算界面和阶跃能量，并将其与基于支撑纳米晶体的平衡形状的实验测量进行比较。实验部分利用了电子显微镜的最新发展，可实现界面处氧原子的成像以及通过深度切片对界面结构进行 3D 成像。从理论上讲，将使用能量密度方法来计算表面和界面处的能量分布。该计划建立在平坦金红石 (110) 表面支撑的金纳米晶体方面取得的进展的基础上，并将研究扩展到邻接表面，以实现阶跃能量的测量。