Berlin 2008 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 20: Glasses III (joint session DF/DY)

DY 20.2: Talk

Wednesday, February 27, 2008, 14:45–15:00, EB 407

Decoupling of Atomic Diffusion in Glass-Forming Mixtures — •Thomas Voigtmann and Jürgen Horbach — Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln

The diffusion in dense binary soft-sphere mixtures with disparate sizes is studied. While the system approaches a glass transition, only the transport of large particles ceases, while small particles are still able to diffuse through the almost frozen background formed by the large ones, leading to an order-of-magnitude decoupling in the respective transport coefficients. This mechanism qualitatively describes the phenomenology of ion-conducting melts such as sodium silicate mixtures. Upon further increasing the density, the small-particle mean-squared displacement shows an increasing regime of anomalous power-law-like diffusion, which is interpreted as the precursor of a second localization transition following the glass transition in this system.