High heat fluxes and increased temperatures have led to major road blocks in the advancement of materials and technologies. For example, high frequency devices and optical links, energy storage and conversion devices, and high power laser systems have all demonstrated thermal failures that prevent functional material composites from reaching their full theoretical potential. These composites devices rely on a multitude of thin film materials with varying levels of dopants and defects in addition to a high density of material interfaces. In these nanoscale materials, unique phonon transport properties and processes can give rise to thermal conductivities that are drastically different than their bulk counterparts.
In this talk, I will discuss our work in which we are using nanoscale defects and interfaces to study unique phonon thermal transport properties in materials with the end goal of providing means to realize “user defined” thermal conductivities of materials. Traditionally, defects and interfaces are viewed as detrimental to thermal conductivity, and can lead to device overheating and failure. However, as I will discuss, by understanding how phonons interface with nanoscale defects and interfaces, the thermal conductivity of materials can be “prescribed” or “controlled”. Thus, I will discuss how to use defects and interfaces to both actively and passively control the thermal conductivity of solids.
Patrick E. Hopkins is a Professor in Department of Mechanical and Aerospace Engineering at the University of Virginia, with courtesy appointments in the Department of Materials Science and Engineering and the Department of Physics. Patrick received his Ph.D. in Mechanical and Aerospace Engineering at the University of Virginia in 2008. His dissertation research was focused on developed pulsed laser-based diagnostics to measure temperature and energy transfer in solid materials. Prior to his PhD, Patrick graduated from the University of Virginia with majors in Mechanical Engineering and Physics in 2004.
After his Ph.D., Patrick was one of two researchers in the nation to receive a Truman Fellowship from Sandia National Laboratories in 2008. Under this Fellowship, Patrick worked at Sandia in Albuquerque, NM from 2008 – 2011 developing novel laser-based diagnostics to measure temperature and energetic processes in solid nanosystems and across interfaces adjacent to solid and liquids. In 2011, Patrick returned to the University of Virginia as an Assistant Professor, and was promoted to Associate Professor with Tenure in 2015, and Full Professor in 2018. Patrick’s current research interest are in energy transport, charge flow, laser-chemical processes and photonic interactions with condensed matter, soft materials, liquids, vapors and their interfaces. Patrick’s group at the University of Virginia uses various optical thermometry-based experiments to measure the thermal conductivity, thermal boundary conductance, thermal accommodation, strain propagation and sound speed, and electron, phonon, and vibrational scattering mechanisms in a wide array of bulk materials and nanosystems.
In the general fields of nanoscale heat transfer, laser interactions with matter, and energy transport, storage and capture, Patrick has authored or co-authored over 190 technical papers (peer reviewed), been awarded 3 patents focused on materials, energy and laser metrology. The research in Patrick’s lab is currently being funded by DARPA, ONR, AFOSR, ARO, Rolls-Royce, NSF, and Western-Digital. Patrick has been recognized for his accomplishments via an Air Force Office of Scientific Research Young Investigator Award, an Office of Naval Research Young Investigator Award, the ASME Bergles-Rohsenhow Young Investigator Award in Heat Transfer, and a Presidential Early Career Award for Scientists and Engineering, for which Patrick met President Barack Obama in 2016.