Long-term physical ageing in As–Se glasses with short chalcogen chains

R. Golovchak, O. Shpotyuk, A. Kozdras, M. Vlcek, B. Bureau, A. Kovalskiy and H. Jain.

Journal of physics: condensed matter, vol. 20, 2008, p. 245101.

Abstract

Long-term physical ageing of chalcogenide glasses, which occurs over tens of years, is much less understood than the short-term ageing. With Se-rich underconstrained As₃₀Se₇₀ glass as a model composition (consisting of Se_n chains with n ≤ 3 on average), a microscopic model is developed for this phenomenon by combining information from differential scanning calorimetry, extended x-ray absorption fine structure, Raman, and ⁷⁷Se solid state nuclear magnetic resonance spectroscopies. The accompanying changes in the electronic structure of these glasses are investigated by x-ray photoelectron spectroscopy. The data suggest ageing from cooperative relaxation, presumably involving bond switching or reconfiguration of As–Se–Se–As fragments.