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

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.