High-Pressure Transformation of SiO₂ Glass from a Tetrahedral to an Octahedral Network

Anita Zeidler, Kamil Wezka, Ruth F Rowlands, Dean A J Whittaker, Philip S Salmon, Annalisa Polidori, James W E Drewitt, Stefan Klotz, Henry E Fischer, Martin C Wilding, Craig L Bull, Matthew G Tucker, Mark Wilson

OAI: oai:purehost.bath.ac.uk:publications/030979f5-e13c-492a-b61e-7420d6f408e8 • DOI: https://doi.org/10.1103/PhysRevLett.113.135501

A combination of in situ high-pressure neutron diffraction at pressures up to 17.5(5) GPa and molecular dynamics simulations employing a many-body interatomic potential model is used to investigate the structure of cold-compressed silica glass. The simulations give a good account of the neutron diffraction results and of existing x-ray diffraction results at pressures up to ∼60  GPa. On the basis of the molecular dynamics results, an atomistic model for densification is proposed in which rings are "zipped" by a pairing of five- and/or sixfold coordinated Si sites. The model gives an accurate description for the dependence of the mean primitive ring size ⟨n⟩ on the mean Si-O coordination number, thereby linking a parameter that is sensitive to ordering on multiple length scales to a readily measurable parameter that describes the local coordination environment.