Heteroepitaxial Metal Nanostructure Diffusion Through Collective Slip

通过集体滑移的异质外延金属纳米结构扩散

• 批准号: 0703995
• 负责人: John Weaver
• 金额: --
• 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: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0703995&HistoricalAwards=false
• 关键词: Heteroepitaxial; Metal; Nanostructure; Diffusion; Through

TECHNICAL: This transformative, high-risk, high-payoff project would investigate the collective migration dynamics of metal nanostructures via the glide of misfit dislocations through the interface. The project has experimental and theoretical aspects that build on the strengths of the two principal investigators. A feasibility study done with low-temperature scanning-tunneling microscopy (STM) showed the diffusion of two- and three-dimensional Cu nanostructures on Ag(111). PIs suggest that the mechanism involves the formation and glide of misfit dislocations through the interface. The experimental component would use low-temperature STM to capture island diffusion dynamics, to establish the size- and temperature-dependence of diffusivity, and to link structural changes within the island to collective motion of the entire structure. PIs would investigate diffusion for Cu/Ag(111), for two other fcc systems, Cu/Au(111) and Pd/Ag(111), and for two bcc systems, Fe/W(110) and Fe/Nb(110). These systems were chosen so that PIs could explore the parameter space of lattice mismatch, bond strength, and crystal structure. Atomistic simulations would directly connect to experiment by employing (1) atomistic calculations of island structure as a function of size, (2) temperature-accelerated dynamics simulations of nanostructure diffusion to study mechanisms, and (3) electronic-structure methods to accurately predict the energy barriers associated with those mechanisms. NON-TECHNICAL: Nanoparticle diffusion through dislocation glide has never been observed before. It has been modeled in theory and simulation but that work did not attempt to predict the dynamics of motion. Through experiment and simulations, PIs would be able to study a new phenomenon for surfaces and interfaces that should have important implications. Misfit dislocations are ubiquitous in strained heteroepitaxy, which is important for materials technologies that include heterogeneous catalysis and microelectronics. Education and training are key components of the program. Students would work with senior group members while they become familiar with the laboratory. They would participate fully in the preparation of manuscripts, both their own and those of other group members, and of proposals such as this one. They are expected to compete for student prizes and to present papers at conferences. They are also expected to contribute to the education of younger students. Undergraduate students are fully integrated, and their contributions are reflected by co-authorship of publications. PIs' laboratories are open for visits by prospective undergraduate and graduate students; freshmen involved in Engineering Open House and upperclassmen involved in senior design projects benefit from access to them.

技术支持：这个变革性的，高风险的，高回报的项目将通过界面失配位错的滑动来研究金属纳米结构的集体迁移动力学。该项目具有实验和理论方面的优势，建立在两个主要研究者。用低温扫描隧道显微镜（STM）进行的可行性研究显示了二维和三维Cu纳米结构在Ag（111）上的扩散。PI表明，该机制涉及通过界面的失配位错的形成和滑移。实验部分将使用低温STM来捕获岛扩散动力学，建立扩散率的大小和温度依赖性，并将岛内的结构变化与整个结构的集体运动联系起来。PI将研究Cu/Ag（111）、另外两个面心立方体系Cu/Au（111）和Pd/Ag（111）以及两个体心立方体系Fe/W（110）和Fe/Nb（110）的扩散。选择这些系统是为了使PI能够探索晶格失配、键强度和晶体结构的参数空间。原子模拟将通过采用（1）岛结构的原子计算作为大小的函数，（2）纳米结构扩散的温度加速动力学模拟来研究机制，以及（3）电子结构方法来准确预测与这些机制相关的能垒，从而直接连接到实验。非技术性：以前从未观察到纳米颗粒通过位错滑移扩散。它已经在理论和模拟中建模，但这项工作并没有试图预测运动的动力学。通过实验和模拟，PI将能够研究具有重要意义的表面和界面的新现象。失配位错在应变异质外延中普遍存在，这对于包括多相催化和微电子学在内的材料技术是重要的。教育和培训是该方案的关键组成部分。学生将与资深小组成员一起工作，同时熟悉实验室。他们将充分参与起草他们自己的和其他小组成员的文稿，以及诸如本提案这样的提案。他们将参加学生竞赛，并在会议上发表论文。他们还被期望为年轻学生的教育做出贡献。本科生是完全集成，他们的贡献是通过出版物的合著反映。PI的实验室向未来的本科生和研究生开放参观;参与工程开放日的新生和参与高级设计项目的高年级学生可以从中受益。