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DY: Dynamik und Statistische Physik
DY 35: Glasses I (joint session DF/DY)
DY 35.6: Talk
Monday, March 7, 2005, 11:30–11:45, TU A060
Intermediate range order and transport processes in viscous aluminium silicates: A computer simulation study — •Patrick Pfleiderer, Jürgen Horbach, and Kurt Binder — Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
Glassforming mixtures of SiO2 with Al2O3 with different compositions are investigated by molecular dynamics (MD) computer simulations. These systems form tetrahedral network structures, i.e. both Al and Si are four-fold coordinated by oxygens. We show that these systems exhibit intermediate range order (IRO) that is reflected by prepeaks in partial static structure factors around 0.5 Å−1. The underlying structure is a microphase-separated system where Al-O-rich regions form a percolating network through the Si-O structure. We study how the latter IRO is reflected in dynamical quantities such as the Debye-Waller factor and wave-vector dependent relaxation times.In the temperature range under investigation, i.e. for T>2000 K, structural relaxation can be well described by mode coupling theory.