We demonstrate that grain boundaries (GBs) behave as Brownian ratchets, exhibiting direction-dependent mobilities and unidirectional motion under oscillatory driving forces or cyclic thermal annealing. We observed these phenomena for nearly all nonsymmetric GBs but not for symmetric ones. Our observations build on molecular dynamics and phase-field crystal simulations for a wide range of GB types and driving forces in both bicrystal and polycrystalline microstructures. We corroborate these simulation results through in situ experimental observations. We analyze these results with a Markov chain model and explore the implications of GB ratchet behavior for materials processing and microstructure tailoring.
Professor David Srolovitz is the author of ~560 research papers on materials theory/simulations of defects, microstructure, deformation, and film growth. He has an h-index of over 112 and ~45,000 citations. He is a Member of the US National Academy of Engineering, Fellow of MRS, TMS, ASM, Institute of Physics and won the MRS Materials Theory Award. He was professor at Princeton University, the University of Pennsylvania, and the University of Michigan, was staff at Los Alamos National Lab and Exxon Corporate Research. He held positions in materials science, mechanical engineering, computer science, physics, applied physics, theoretical physics and applied mathematics.
Clean water and clean air are vital for public health. This project focuses on developing high-efficiency and environmentally sustainable filters for removing harmful air/water pollutants. The team has developed novel architectures and functionalities for the filters to achieve high permeance, high removal efficiency, and excellent reusability.
