Very long physical ageing in inorganic polymers exemplified by the GexSe1-x vitreous system

The effects of very long physical ageing up to 13yr on vitreous chalcogenide glasses have been investigated for GexSe1-x glasses, x=4, 8 and 12at%, by means of calorimetric methods. We show that the rejuvenation of such very old materials can be performed without any problem. More importantly, we find that a long ageing leads to a phase separation process. This could explain why the configurational (or conformal entropy) does not apparently reach its equilibrium value as already observed by Gomez Ribelles et al. (Macromolecules 28 (1995) 5867) on other polymeric materials.