CAREER: Engineering Thermal Energy Transport Using Embedded Nanoparticles

工程热能传输使用嵌入式纳米粒子这个项目探讨了嵌入式颗粒材料中的热传递的基本物理。 许多材料中的热流是通过称为声子的随机振动发生的，声子以波的方式传输能量。 声子与它们遇到的任何杂质（包括粒子）相互作用，可能导致能量散射，从而阻碍热量的流动。 该项目的目标是利用新的理论，计算和实验技术来了解声子如何与纳米粒子相互作用，并利用这些信息来设计具有改进热性能的材料。 该项目的科学发现可能会导致具有改善散热能力的纳米结构电子和光学材料，以及以前所未有的效率将热量直接转换为电力的热电材料。 该项目还旨在为社会提供更广泛的影响，包括（1）与4 Youth Production非营利组织合作执行教育推广计划，使DE威尔明顿的K-8高危儿童接触光学，传热，节能（2）执行针对工业用户的教育推广计划，目标是将超快热测量技术转移到非学术性的终端用户。 特别是，该项目探讨了两个主要的科学假设：（1）米氏散射对传输的重要性远远超过以前认识到的，这改变了纳米复合材料热控制的几何和材料设计规则，以及（2）本地化可能会支配对致密纳米颗粒合金材料中的热传输重要的长波长声子的物理学。 使用连续介质力学的精确结果，该项目探讨了与米氏散射机制相关的复杂干涉效应如何改变设计策略，例如在试图控制热传输时选择纳米颗粒尺寸，成分和纳米颗粒形状。 采用新发展的原子论计算方法，给出了任意几何结构下与极化和波数相关的声子散射截面，并结合声子-声子和声子-合金散射率的第一性原理计算，预测了不同模式下的热输运性质;该方法将使得能够模拟前所未有的尺寸尺度的声子-结构散射问题，我们用它来研究致密纳米复合材料中声子局域化的物理学。 通过对纳米颗粒合金材料进行相应的热输运测量，该项目寻求实验证据和对三维声子局域化的理解。

Engineering Thermal Energy Transport Using Embedded NanoparticlesThis 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.