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

¹ Graduate School of Science and Engineering, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan
² Department of Physics, Faculty of Science, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan

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.