Reversibility Window, Aging, and Nanoscale Phase Separation in GexAsxS1-2x Bulk Alloy Glasses

TL;DR

This study investigates the reversibility window in GexAsxS1-2x glasses, revealing a composition range with minimal aging and stress-free networks, and explores how nanoscale phase separation influences structural stability.

Contribution

It identifies the compositional range of the reversibility window in GexAsxS1-2x glasses and links structural features to aging behavior and phase separation.

Findings

Reversibility window occurs at 0.11 < x < 0.15 with minimal non-reversing enthalpy.

Aging occurs outside the window but not within it.

Structural analysis shows presence of monomers affecting network rigidity.

Abstract

The non-reversing enthalpy near Tg, DHnr, in bulk GexAsxS1-2x glasses is found to display a global minimum (~0) in the 0.11 < x < 0.15 range, the reversibility window. Furthermore, the DHnr term is found to age for glass compositions both below (x < 0.11) and above (x > 0.15) the window but not in the window. Glass compositions in the window are rigid but stress-free, those below the window are floppy, and those above the window are stressed-rigid. Raman scattering shows floppy and stressed rigid networks to consist in part of monomers. The latter aspect of structure narrows the width of the reversibility window and suppresses in part aging effects observed outside the window in contrast to those in the fully polymerized selenide counterparts.