High-pressure plastic deformation of lead metasilicate glass accessed by Raman spectroscopy: Insights into the Qn distribution

Abstract In this study, lead metasilicate glasses (PbSiO3) were densified at different maximum pressures in a diamond anvil cell (DAC) at room temperature. The densified glass samples were investigated ex-situ by Raman spectroscopy to probe their pressure-induced plastic deformation limit and permanent structural modifications on the Qn distribution. With a high Pb content, this glass exhibits a low elastic limit at ~4 GPa, which is linked to an initial compact structure. Spectral curve fitting of the high-frequency region of the Raman spectra, consisting of symmetric Si-O stretching modes, exhibit subtle Qn population modifications with maximum pressure. This reveals silica network depolymerization where the proportion of non-bridging oxygens (NBO) increases at the expense of bridging oxygens (BO). Possible densification mechanisms are discussed in contrast to those known in other silicate glasses.