Atomistic mechanism of physical ageing in glassy materialsM. Warren and J. Rottler
Department of Physics and Astronomy, The University of British Columbia - 6224 Agricultural Road, Vancouver, BC, V6T 1Z1, Canada
received 14 July 2009; accepted in final form 16 November 2009; published December 2009
published online 15 December 2009
Using molecular simulations, we identify microscopic relaxation events of individual particles in ageing structural glasses, and determine the full distribution of relaxation times. We find that the memory of the waiting time tw elapsed since the quench extends only up to the first relaxation event, while the distribution of all subsequent relaxation times (persistence times) follows a power law completely independent of history. Our results are in remarkable agreement with the well-known phenomenological trap model of ageing. A continuous-time random walk (CTRW) parametrized with the atomistic distributions captures the entire bulk diffusion behavior and explains the apparent scaling of the relaxation dynamics with tw during ageing, as well as observed deviations from perfect scaling.
81.05.Kf - Glasses (including metallic glasses).
64.70.Q- - Theory and modeling of the glass transition.
05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.
© EPLA 2009