Viscosity, enthalpy relaxation and liquid-liquid transition of the eutectic liquid Ge15Te85

Abstract The viscosity and enthalpy relaxation in the Ge15Te85 eutectic liquid are investigated using a combination of parallel plate rheometry and conventional and modulated differential scanning calorimetry (DSC). The results of these measurements provide evidence for similar temperature dependence of enthalpy and shear relaxation timescales in this liquid. However, the enthalpy relaxation is found to be more than an order of magnitude slower than the shear relaxation process. The temperature dependence of the viscosity of the Ge15Te85 liquid in the supercooled state and above its melting point can be described using a single fragility index, except over a narrow temperature region in the immediate vicinity of the melting point where the viscosity abruptly increases, signifying a liquid-liquid transition. This anomalous viscosity jump coincides with the onset of an exothermic event observed in the DSC cooling curve. Together, these results are consistent with a transition that involves incipient liquid-liquid immiscibility that can be bypassed via rapid supercooling.