CORRELATIONS OF THE NONEXPONENTIALITY AND STATE DEPENDENCE OF MECHANICAL RELAXATIONS WITH BOND CONNECTIVITY IN GE-AS-SE SUPERCOOLED LIQUIDS

We have studied the mechanical responses of supercooled Ge-As-Se liquids to flexural strains and temperature steps. The departures from exponential relaxation correlate well with the variations in connectivity. The structural state dependence of the mechanical relaxation, detected in pure and weakly cross-linked Se, is suppressed completely at the rigidity percolation threshold <r(c)>, where the liquid fragility is a minimum. The shapes of the decay functions of samples with the same <r(c)> but different compositions are not universal at T(g) probably because of chemical effects near the binary edges of the ternary system.