| To study elastic phase transitions in glasses will help us to understand the basic structure and the properties of the glass systems. The physical picture emerging in this field suggests that one can generically classify inorganic glasses into three distinct phases, floppy-intermediate-stressed rigid. Weakly crosslinked networks in which the count of Lagrangian bonding constraints per atom, nc, is less than 3 belong to floppy phases. Optimally crosslinked networks in which nc is near 3, are isostatically rigid and serve to define intermediate phases. On the other hand, strongly crosslinked networks in which the count of nc is greater than 3 belong to stressed rigid phases. Here the count of 3 comes from the degrees of freedom associated with an atom in a 3d network.; In this work, the three elastic phases have been identified in the Ge xAsxSe1-2x and GexAsxS 1-2x system through MDSC and Raman Scattering measurements. Mossbauer Spectroscopy has also been performed to understand the molecular structure in the mentioned systems. And due to the existence of the existence of the nanoscale monomers in the S system, we find the lower limit of the intermediate phase has been upshifted compared to that of the Se system. In the Se system, elastic power law has been identified in both the intermediate phase and the stressed-rigid phase.; Also in this work, for the first time, we identified the three phases in three oxide systems, (Na2O)x(SiO2) 1-x, (K2O)x(SiO2)1-x , (Na2O)x(B2O3)1-x with the help of MDSC and Raman Scattering measurements. The molecular structure of the systems was studied through Raman Scattering and Brillouin measurements.; Our experimental results also show that for glass compositions in the intermediate phase, there is no natural aging effect at least in the period of 3 years. And there is also no light assisted aging occurring for these samples. While for compositions in both the stressed-rigid and floppy phase, glasses are found to age with the waiting or irradiation time with a stretched exponential function. |
