Melt Dynamics and Glass Topological Phases in the Ge_yAs_ySe_100-2y Ternary

Recently one found^1,2 that the Fragility index (m) of dry and homogenized binary Ge_x (Se or S)_100-x melts are super- strong ( m < 20) in the 20% < x < 26% range (fragility window) and fragile elsewhere. Ab initio MD simulations confirmed³ the behavior. Furthermore, the enthalpy of relaxation of corresponding glasses was found to be near vanishing in the same 20% < x < 26% range, the reversibility window. Is the correlation between the fragility window and reversibility window generic? To explore the issue further, we now examine the Ge_yAs_ySe_100-2y ternary. Dry and homogeneous melts/glasses were synthesized in the 0 < y < 25% range, and their homogeneity confirmed using FT-Raman profiling. The fragility index and the reversibility window are being measured using Modulated DSC (Complex Cp analysis at variable modulation frequency and Enthalpy of relaxation at a fixed modulation frequency). Results of these experiments will be presented.

1. K. Gunasekera et al. J. Chem. Phys.139, 164511 (2013).
2. S. Chakraborty et al. J. Phys. Chem. B 118, 2249 (2014).
3. C. Yildrim et al. Nature Communications 7, 11086(2016)