Density hardening plasticity and mechanical aging of silica glass under pressure: A Raman spectroscopic study

TL;DR

This study uses Raman spectroscopy to analyze how silica glass undergoes permanent densification and mechanical aging under pressure, revealing a density hardening phenomenon linked to the maximum pressure experienced.

Contribution

It introduces the concept of density hardening and mechanical aging in silica glass, correlating densification saturation with maximum pressure and structural packing.

Findings

Raman spectroscopy effectively tracks silica's plastic behavior under pressure.

Densification saturation relates to densest tetrahedral packing.

Residual densification evolves as a density hardening phenomenon.

Abstract

In addition of a flow, plastic deformation of structural glasses (in particular amorphous silica) is characterized by a permanent densification. Raman spectroscopic estimators are shown to give a full account of the plastic behavior of silica under pressure. While the permanent densification of silica has been widely discussed in terms of amorphous-amorphous transition, from a plasticity point of view, the evolution of the residual densification with the maximum pressure of a pressure cycle can be discussed as a density hardening phenomenon. In the framework of such a mechanical aging effect, we propose that the glass structure could be labelled by the maximum pressure experienced by the glass and that the saturation of densification could be associated with the densest packing of tetrahedra only linked by their vertices.