Abstract & Overview
Recovered density is commonly used to describe the structural state of densified silica glass, although its ability to uniquely predict mechanical behaviour remains uncertain. Here, molecular dynamics simulations were performed to investigate whether different pressure–temperature histories produce mechanically distinct amorphous SiO₂ glasses despite nearly identical recovered densities. Reference, cold-compressed, and hot-compressed glasses were prepared under controlled conditions, followed by structural characterization using radial distribution functions, ring statistics, void analysis, and static structure factors. Mechanical behaviour was evaluated through small-strain elasticity, loading–unloading simulations, and non-affine displacement analysis. The cold- and hot-compressed glasses differed in recovered density by only 0.21%, yet retained distinct medium-range topologies. Relative to the cold-compressed glass, the hot-compressed glass exhibited a higher Young's modulus (85.4 ± 1.1 versus 82.6 ± 1.0 GPa), higher yield stress (7.48 ± 0.16 versus 7.05 ± 0.18 GPa), and approximately 31% lower residual strain. Irreversible deformation preferentially originated near strained small-ring environments, while incorporating ring topology and void connectivity substantially improved the prediction of mechanical response compared with density alone. These findings demonstrate that preparation-dependent medium-range topology is a key structural descriptor governing the mechanical behaviour of amorphous SiO₂ beyond recovered density.