Temperature-Dependent Defect Dynamics in the Network Glass SiO2

Abstract

We investigate the long time dynamics of a strong glass former, SiO2, below the glass transition temperature by averaging single particle trajectories over time windows which comprise roughly 100 particle oscillations. The structure on this coarse-grained time scale is very well defined in terms of coordination numbers, allowing us to identify ill-coordinated atoms, called defects in the following. The most numerous defects are OO neighbors, whose lifetimes are comparable to the equilibration time at low temperature. On the other hand SiO and OSi defects are very rare and short lived. The lifetime of defects is found to be strongly temperature dependent, consistent with activated processes. Single-particle jumps give rise to local structural rearrangements. We show that in SiO2 these structural rearrangements are coupled to the creation or annihilation of defects, giving rise to very strong correlations of jumping atoms and defects.

10 pages, 17 figures

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Cited by in corpus (3)

• Universal low-frequency vibrational modes in silica glasses
• Elementary plastic events in amorphous silica
• Universal Scaling in the Aging of the Strong Glass Former SiO${}_2$