Physical aging of selenium glass: Assessing the double mechanism of equilibration and the crystallization process

This work focuses on the study of the physical aging of a selenium glass by differential scanning calorimetry (DSC) and fast scanning calorimetry (FSC). Aged samples of 30 and 40 years old at room temperature were analysed by classical DSC, and their enthalpies of recovery were calculated, showing that the glass has reached its thermodynamic equilibrium and is stable over time. The study of accelerated physical aging by using FSC on a rejuvenated sample allows reproducing the way by which this glass has reached its thermodynamic equilibrium at the laboratory time scale. We evidence that the glass reaches its equilibrium state in one or two steps, depending on the gap between the aging temperature and the glass transition temperature, resulting from the difference in the mechanisms governing the relaxation process. Furthermore, a second phenomenon is evidenced, consisting in the crystallization of the glass once the equilibrium has been reached for aging temperatures close to the glass transition temperature.

Automated summary

This study focused on the physical aging of a selenium glass through DSC and FSC, showing that the glass reaches thermodynamic equilibrium and stability over time. By using FSC on rejuvenated samples, the study reproduced the way the glass reaches equilibrium at the laboratory time scale, revealing that the glass can reach equilibrium in one or two steps depending on the aging temperature. Additionally, a second phenomenon was observed where the glass crystallizes once equilibrium is reached at temperatures close to the glass transition temperature.