Berlin 2005 – scientific programme

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DF: Dielektrische Festkörper

DF 7: Gl
äser I (gemeinsam mit FV DY)

DF 7.6: 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.