Collective Dynamics and Resonances of Phonons and Dislocations in Thermal Transport

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NONTECHNICAL SUMMARYThis award supports research that will use atomic resolution computer models to determine the nature of interactions between dislocations and atomic vibrations in crystalline materials. Dislocations are ubiquitous defects that involve a sudden irregularity (such as the appearance of an extra row of atoms) in the atomic arrangement of crystalline materials. They often can move through the material when the material is under thermal or mechanical loading. The atoms in a crystal vibrate, with the amplitude of the vibrations increasing with temperature. The movement of dislocations through the crystal can be affected by their interactions with these vibrations in a manner similar to the effect that waves have on the motion of a boat as it moves through the water. This research will quantify such interactions and determine their effect on heat transport through the material. The results of this research will be of fundamental importance to the design of new materials for many applications of heat transport, such as thermoelectrics that can convert heat to electrical energy for a green economy. This award also supports the team’s educational and outreach activities. The PIs will design computational lecture series and mini projects to train undergraduate students every summer during the period of this project. The PIs will also reach out to women and minority students, and students with physical disabilities, to explore their research interests and provide them with research experiences. The datasets and source codes developed under this project will be made freely available to the computational materials science community. The research team will also organize a symposium at an international or national conference on the role of interactions of dislocations with crystal vibrations on heat transport.TEHCNICAL SUMMARYThis award supports research that will elucidate the microscopic processes that describe the interaction between dislocations and phonons and their implications for macroscopic materials phenomena, including plastic flow, internal friction, and thermal resistance. A general description for phonon-dislocation interaction that can provide a quantitative agreement with major experimental results has been a significant challenge, which has limited our understanding of this interaction as well as its effect on thermal transport. This research aims to address this challenge by establishing a multiscale methodology from machine learning of high-fidelity interatomic potentials to concurrent atomistic-continuum simulation of coupled dislocations dynamics and phonon transport. This will enable an accurate description of dislocations in the studies of phonon thermal transport, as well as a visualization of the transient processes of phonon scattering with multiscale details of the physical processes to identify the underlying mechanisms. This award also supports the team’s educational and outreach activities. The PIs will design computational lecture series and mini projects to train undergraduate students every summer during the period of this project. The PIs will also reach out to women and minority students, and students with physical disabilities, to explore their research interests and provide them with research experiences. The datasets and source codes developed under this project will be made freely available to the computational materials science community. The research team will also organize a symposium at an international or national conference on the role of interactions of dislocations with crystal vibrations on heat transport.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.