Collaborative Research: Hierarchically Structured Polycrystalline Hollow Gold Nanoparticles- A Model System for Integrated Experimental and Multiscale Computational Nanomechanics

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

Collaborative Proposal: Hierarchically Structured Polycrystalline Hollow Gold Nanoparticles- A Model System for Integrated Experimental and Multiscale Computational Nanomechanics Abstract This collaborative grant between the University of Texas at Arlington (UTA) and University of Minnesota (UMN) funds a combined experimental and theoretical/computational research program that aims to gain fundamental understanding into the mechanics of hierarchically structured gold nanospheres. Multiple length scales such as grain size, shell thickness, and diameter of sphere exist within an individual structure. Specifically, our gold nanospheres are about 100 nm in diameter, and feature a polycrystalline shell with a thickness ranging from 20 to 50 nm, and grain size around 5 nm. Such combination provides a ?golden? opportunity to explore the effects of structural hierarchy on the deformation mechanisms of nanoscale materials. Due to their hollow nature, the gold nanospheres can be easily observed and tested with in-situ TEM nanoindentation without elaborate sample preparation. They can be positioned precisely into an addressable array using the ?electrostatic funneling method?. This greatly facilitates nanoindentation experiments, enabling a statistical examination. Model polycrystalline hollow nanoparticles with similar characteristics will be simulated with state-of-the-art multiscale theoretical/computational techniques that combine Molecular Dynamics and Discrete Element Method. Experimental input from the in-situ TEM nanoindentation will greatly facilitate the multiscale modeling, specifically the critical issues of time-acceleration and coarse-graining. The obtained simulation results will help comprehend experimental data and identify deformation mechanisms with atomistic resolution. The general mechanical behavior of nanoscale metals is of great interest for technological applications such as new ultrastrong structural materials, microelectronics and micro- and nano-electromechanical devices and systems. If successful, this research will help establish important design principles targeting such applications. The proposed combination of Molecular Dynamics with Distinct Element Method to tackle problems at different length scales is expected to find broad applications in the modeling community. The proposed research program is integrated with a multi-layered education and outreach program that includes development of new courses designed to educate students in an interdisciplinary field, summer camps for K-12 students, and outreach activities through MRSEC-UMN, existing REU, cyber module development, and demonstrations at high schools and the Science Museum of Minnesota. A coordinated outreach plan in partnership with the Society for Hispanic Professional Engineers is proposed to provide opportunities to underrepresented groups by targeting and involving the large Hispanic population in the State of Texas, which includes a minority recruitment program, a SciTech Latino Summer Camp for K-12 Hispanic students, and a public awareness component.