CAREER: Engineering Thermal Energy Transport Using Embedded Nanoparticles

University Of Delaware, Newark DE

Investigators

Abstract

Engineering Thermal Energy Transport Using Embedded Nanoparticles This project explores the fundamental physics of heat transfer in materials with embedded particles. Heat flow in many materials occurs by random vibrations, called phonons, that transport energy in a wave-like manner. Phonons interact with any impurities they encounter, including particles, potentially leading to energy scattering that impedes the flow of heat. The goal of this project is to leverage new theoretical, computational, and experimental techniques to understand how phonons interact with nanoparticles, and to use that information to engineer materials with improved thermal properties. The scientific findings from this project could lead to nanostructured electronic and optical materials with improved heat dissipation capabilities, and thermoelectric materials that directly convert heat to electricity and vice versa with unprecedented efficiency. The project also seeks to provide a broader impact to society including (1) execution of an educational outreach program in collaboration with the 4Youth Production non-profit organization that exposes at-risk K-8 children in Wilmington, DE to optics, heat transfer, and energy conservation (2) execution of an educational outreach program targeted to industrial users with the goal of transferring ultrafast thermal measurement technology to non-academic end-users. In particular, the project explores two primary scientific hypotheses: (1) that Mie scattering is far more important to transport than previously recognized and this changes the geometric and materials design rules for thermal control of nanocomposites, and (2) that localization may govern the physics of long-wavelength phonons important to thermal transport in dense nanoparticle-in-alloy materials. Using exact results from continuum mechanics, the project explores how complex interference effects associated with operating in the Mie scattering regime alter design strategies such as the choice of nanoparticle size, composition, and nanoparticle shape when trying to control thermal transport. A newly developed atomistic computational method is employed to provide polarization- and wavenumber-dependent phonon scattering cross sections in arbitrary geometries, and integrated with first-principles calculations of phonon-phonon and phonon-alloy scattering rates to predict thermal transport properties on a mode-by-mode basis; the method would enable phonon-structure scattering problems of unprecedented size scale to simulated, which we use to investigate the physics of phonon localization in dense nanocomposites. By performing corresponding thermal transport measurements on nanoparticle-in-alloy materials, the project seeks experimental evidence and understanding of 3-dimensional phonon localization.