Influence of fictive temperature and composition of silica glass on anomalous elastic behaviour

TL;DR

This study investigates how the thermal history and water content influence the elastic properties of silica glass, revealing that water content has a more significant impact than fictive temperature, with unique behaviors observed near the glass transition.

Contribution

It provides new insights into the effects of fictive temperature and OH content on silica glass's elastic behavior, highlighting the dominant role of water content over thermal history.

Findings

Elastic modulus increases anomalously in glassy and supercooled states.

Water content significantly affects elastic moduli more than thermal history.

A decrease in shear moduli above 1223K in hydrated samples was observed.

Abstract

In order to point out the influence of thermal history (fictive temperature) and OH content on the elastic properties of silica glass, we have performed high resolution in situ Brillouin spectra of SiO2 glass from room temperature to the supercooled liquid at 1773K across the glass transition. The well known anomalous increase of elastic modulus in the glassy state and in the supercooled liquid regime is observed. No change of slope in the elastic moduli of silica appears as a characteristic of glass transition, on the contrary to what happens in various other glasses. We show that thermal history has a weak effect on elastic moduli in the glass transition regime for silica glass. The effect of water content in silica glass is more efficient than the fictive temperature effect and gives larger changes in the amplitude of elastic modulus for the same thermal dependence. A singular decrease above 1223K is also observed in the shear moduli for hydrated samples. Different models explaining elastic properties temperature dependence in relationship with frozen-in density fluctuations or with the structure are discussed.