Carbon Nanostructures: Surface-Mediated Mechanical Response and Topologically Constrained Bonding

技术概述：该奖项支持纳米尺度材料研究领域的计算和理论研究和教育。通过计算机模拟，该项目开发了几种适用于纳米级应用的新型材料和基于材料的系统。一种正在开发的材料是一种二维铁电片，由单层的阳离子和阴离子夹在石墨片上组成。系统研究了卤素、硫族化合物和多原子阴离子补偿的单、双金属阳离子的功能。第二个研究领域涉及由双稳定碳结构组成的纳米机械致动器的发展。根据环境的不同，这些结构可能会弯曲或倒塌。在基板上建造这样的致动器将提供密集的压力依赖的机械记忆装置、气体传感器和悬臂。特别强调的是确定系统可以恢复的临界宽高比、尺寸和屈曲角度，无论是否有迟滞，以及那些导致不可逆变化的条件。第三个相关研究领域涉及同心同轴碳纳米管的开发，以研究开发纳米活塞、螺钉和换能器的可能性。最后一项工作是开发由N2O和NO2分子构建的开放扩展框架。重点是确定产生稳定相所需的压力，并确定它们在较低压力下是否亚稳。这些项目是在大量实验合作的基础上进行的。所有这些问题的共同点是需要和使用精确的密度泛函方法、经验电位和紧密结合的方法来确定电子和振动效应。PI将通过一个以高中生为目标的基于互联网的科学推广活动来传播他的研究成果。非技术总结：该奖项支持计算和理论研究和教育，使用复杂的计算建模技术来确定新型纳米级系统将具有有用功能的环境条件。其中一个重点是确定导致坚硬的轻质碳基纤维弯曲和弯曲的条件。这种纤维可用于制造机械记忆装置和传感器。当这些纤维排列成纳米级同轴电缆时，在小型化活塞、螺钉和换能器方面有进一步的应用。这里的研究集中在这种纤维的即时应用，以及它们在原子和分子的操纵和能量转移方面的应用。基于本文研究的一些碳基材料和纳米系统，正在进行更多的计算机模拟，以研究由氮和氧组成的类似结构的制造。一种轻质的、坚固的碳基薄膜的模拟也在进行中，这种薄膜的一边涂有金属箔，另一边涂有类似聚四氟乙烯的薄片。PI将通过一个以高中生为目标的基于互联网的科学推广活动来传播他的研究成果。

TECHNICAL SUMMARY:This award supports computational and theoretical ressearch and education in the area of materials research at the nanoscale. Through computer simulation, this project develops several new classes of materials and materials-based systems amenable to use for nanoscale applications. One material under development is a two-dimensional ferroelectric sheet composed of monolayers of cations and anions sandwiching a graphite sheet. Systematic investigations as a function of single and double metallic cations compensated by halogens, chalcogenides and polyatomic anions are underway. A second area of investigation deals with the development of nanomechanical actuators composed of bistable carbon structures. Depending upon the environment these structures may either buckle or collapse. Construction of such actuators on substrates will provide for dense pressure-dependent mechanical memory devices, gas sensors and cantilevers. Particular emphasis is on determining critical aspect ratios, sizes and buckling angles at which the system can recover, with or without hysteresis, and those conditions which lead to irreversible alteration. A third related area of investigation deals with the development of concentric coaxial carbon nanotubes to investigate the possibility of developing nanoscale pistons, screws and transducers. The final effort deals with the development of open extended frameworks built from N2O and NO2 molecules. Emphasis is on determining pressures required to create stable phases and determine if they are metastable at lower pressures. These projects are performed in concert with substantial experimental collaboration.Common to all of these problems is the need for and use of accurate density functional methods, empirical potentials and tight-binding methodologies to determined both electronic and vibrational effects. The PI will spread the excitement of his research through an internet-based scientific outreach effort aimed at high-school-age students. NON-TECHNICAL SUMMARY:This award supports computational and theoretical ressearch and education that uses sophisticated computational modeling techniques to determine the environmental conditions at which novel nanoscale systems will operate with useful function. One focus is to determine the conditions that cause stiff lightweight carbon-based fibers to bend and buckle. Such fibers may be used to build mechanical memory devices and sensors. These fibers when arranged as a nanoscale coaxial cable have further applications related to miniaturized pistons, screws and transducers. Research here concentrates on immediate application of such fibers and on their use for manipulation of and energy transfer to atoms and molecules. Based upon some of the carbon-based materials and nanosystems studied here, additional computer simulations which investigate fabrication of similar structures composed of nitrogen and oxygen are underway. Simulation of a lightweight strong carbon-based film coated with a metallic foil on one side and a Teflon-like sheet on the other is also underway. The PI will spread the excitement of his research through an internet-based scientific outreach effort aimed at high-school-age students.