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：这项研究的重点是纳米结构材料研究的基本挑战：如何确定其界面结构和热力学特性。提出了合成的综合，表征和建模工作来应对这一挑战。将测量和计算表面和界面特性，以用于支撑的纳米颗粒，并与结构相关。预计结果将直接影响对技术的重要部分，化学工业的主要组成部分以及令人兴奋的医学诊断新事态发展。这项研究将与外展工作相结合，包括高中访问和本科教育。该研究项目的结果将纳入基于Web的教育材料中，以向学生教授有关结构和衍射，基础架构的研究（请参阅http://emaps.mrl.uiuc.edu/或Google Webemaps）。现在，该特定网站被列为学习电子衍射的最佳网络资源之一。技术摘要：提出了一项合并的实验和理论研究，以确定表面和界面能量以及与原子结构的相关性。在PI组中开发的技术将合成支持氧化物上支持的外延纳米晶体。像差校正的扫描透射电子显微镜（Stem）和透射电子显微镜（TEM）将用于表征Au纳米晶体的平衡形状及其界面结构。 结构数据将用于从第一原理计算界面和步进能，该界面和阶跃能量将与基于支持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，该发展有望在界面上对氧原子进行成像，以及通过深度分段对界面结构进行的3D成像。对于理论，将使用一种能量密度方法来计算表面和界面的能量分布。该程序建立在平面金红石（110）表面上支撑的AU纳米晶体上取得的进展，并将研究扩展到山地表面以实现阶梯能量的测量。