Thermodynamics of liquid-liquid crossover transition in liquid Si15Te85 eutectic alloy

Abstract

Specific heat of liquid Si15Te85 was measured using both the adiabatic scanning calorimetry and modulation calorimetry. The specific heat has a very broad peak around 660°C of which the peak value is 46 J/mol.K. The results are totally different from the previous results that the specific heat is as large as 140 J/mol.K at the liquidus temperature and decreases rapidly with raising temperature. Combining the molar volume and sound velocity as a function of temperature, the thermodynamic susceptibilities, i.e. constant pressure specific heat, isothermal compressibility and thermal expansion coefficient, have been evaluated. Their temperature dependences and magnitudes are in good accordance with the predictions for a crossover transition in a liquid. Comparison is made to a liquid-liquid crossover transition in Ge15Te85 which is sharpest among crossover liquid-liquid transitions of this kind so far found.