Temperature-induced densification of compressed SiO₂ glass: A molecular dynamics study

Abstract

Annealing to several hundred Kelvin has been recently shown to induce densification in compressed SiO₂ glass. By means of an ab-initio parameterised interatomic potential for SiO₂ and molecular dynamic simulations, we studied the structural properties of compressed glass by cold compression at room temperature and by quenching the liquid at selected pressures. The noticeable differences found below 10 GPa between the two results are interpreted in the context of the experimentally reported temperature-induced densification and of the speculated occurrence of a first-order transition between two distinct polyamorphs. Calculated X-ray and neutron structure factors agree well with available experiments, and indicate that structural differences between annealed and cold-compressed forms take place at distances of 3.5–4 Å. In contrast, short-range order (atomic coordination, bond length and angular distribution functions) is identical in the two forms of silica glass.

Keywords:

• SiO₂
• silica glass
• densification
• polyamorphism
• molecular dynamics

Acknowledgements

We thank J. Christie for useful discussions and acknowledge the partial support from CNR/INFM through the ESF program ‘EuroMinSci’.

Additional information

Notes on contributors

Sandro Scandolo

Present address: Department of Civil and Earth Resources Engineering, Kyoto University, Kyoto, Japan