Regensburg 2004 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 28: Glasses I (joint session DF/DY)
DY 28.6: Vortrag
Dienstag, 9. März 2004, 11:15–11:30, H23
The mixed alkali effect in ternary silicates: computer simulation studies — •Hans Knoth, Jürgen Horbach, and Kurt Binder — Institut für Physik, Staudinger Weg 7, Johannes Gutenberg–Universität, D–55099 Mainz
Molecular dynamics computer simulations are used to investigate ternary alkali silicates (1−x)Li2O· xK2O·2SiO2 (0≤ x ≤ 1). These systems are typical ion conductors which is due to a high mobility of the alkali ions. The structure and dynamics is studied for molten systems, as well as at lower temperatures at which only the alkali ions show a diffusive motion. Our aim is to understand the origin of the so-called mixed alkali effect (MAE) which is the phenomenon that the diffusion of the alkali ions is much slower in ternary systems (e.g. x=0.5) than in the corresponding binary systems (i.e. x=0 and x=1). Preferable sites for the alkali diffusion are found that are located in a network of channels. In the ternary system, each alkali species moves in its own channel network leading to a stronger localization of alkali sites and the MAE.