Regensburg 2004 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 4: Gl
äser II (gemeinsam FV DF/DY)

DF 4.10: Vortrag

Dienstag, 9. März 2004, 17:00–17:15, H23

From binary Na-silicate to ternary Na-alumino-silicate melts: the evolution of Na dynamics and intermediate range order — •Florian Kargl¹, Andreas Meyer¹, and Helmut Schober² — ¹Physikdepartment E13, TU München, 85748 Garching — ²Institut Laue-Langevin, 38042 Grenoble, France

Neutron scattering investigations of binary alkali silicate melts revealed correlations on intermediate lengthscales of 6-8 Å. Within MD-simulations on Na-silicates evidence was found that these correlations arise from Na-rich channels percolating in the remaining SiO-network. Fast Na-diffusion takes place via these channels [1]. Substituting the network forming component SiO₂ by GeO₂ leads to a change in structure and in the microscopic transport mechanism, respectively, as verified by inelastic neutron scattering. We present our recent investigations on sodium alumino-silicate melts containing besides SiO₂ a second network former, Al₂O₃. Our main aim was to study the interplay between microscopic dynamics and structure and its influence on macroscopic properties. From quasielastic neutron scattering experiments we conclude that the channel structure is disrupted by adding Al₂O₃ to the Na-silicates resulting in an increase of viscosity as well as a decrease of Na-relaxation times [2].

[1] A. Meyer, J. Horbach, W. Kob, F. Kargl, H. Schober (submitted)

[2] F. Kargl, A. Meyer, Chem. Geol. (submitted)