129I and 119Sn Mossbauer spectroscopy, reversibility window and nanoscale phase separation in binary GexSe1-x glasses

The molecular structure of the prototypical chalcogenide glass system-GexSe1-x in the 00.15, rigid regions nucleate at the expense of floppy ones, and the ratio IB/IA (x) reverses slope to display a global maximum in the 0.200.26, these glasses enter a stressed-rigid elastic phase and in the 0.31<x<13 range nanoscale phase separate into Se-rich and Ge-rich regions. The signature of the latter is saturation of IB/IA (x) at a high value of 1.5 at x=13. 119Sn Mossbauer spectroscopy measurements independently support the picture of broken chemical order of the stoichiometric glass inferred from the 129I Mossbauer experiments. These observations using local probes are well correlated to Raman scattering, modulated differential scanning calorimetric and diffraction measurements