Topological phases, fragility- and reversibility-widows in GexPxSe100-2x ternary*

The fragility index, m, in homogenized chalcogenide melts, are found to display values of m < 20 for compositions that reside in the Intermediate Phase (IP) in the Ge-Se, Ge-S binary systems yielding a fragility window. The enthalpy of relaxation of corresponding glasses, ΔH_nr(x) , becomes minuscule in IP displaying a reversibility window[1]. That correlation between ΔH_nr(x) and m(x) illustrates a basic principle that melt dynamics encode glass topological phases. Here we examine the titled glasses to investigate if the principle extends to the present ternary. We have synthesized titled glasses over a wide range of compositions, 2% < x < 26% by alloying the pure elements in evacuated quartz tubes. Melts were alloyed till the variance in Ge stoichiometry x across the 2 gram batch composition nearly vanished using Raman profiling. In such homogenized glasses we are now examining the variation in ΔH_nr(x) and m(x) using Modulated DSC , and will present the results of these observations. In a previous study[2] variation of ΔH_nr(x) was examined but no attempt to measure the fragility index was made.

1. Boolchand, P., Bauchy, M., Micoulaut, M., Yildirim, C. PSS B 255 (2018)
2. Chakravarty, S., Georgiev, D. G., Boolchand, P., Micoulaut, M. J of Phys: Condensed Matter 17 (2005)