Calorimetric studies of mixing enthalpy in the liquid system Ga-Li, and Ga-Li-Sn

Partial enthalpies of mixing for the liquid phase of the binary Ga-Li and ternary Ga-Li-Sn systems at a temperature of 1081 K were measured by high-temperature drop calorimetry. The binary system was investigated to a maximum lithium content of x(Li) = 0.59. In the ternary, seven composition sections were investigated: x(Ga)/(x(Ga) + x(Sn)) = 0.15, 0.45, 0.70, 0.85, and x(Ga)/(x(Ga) + x(Li)) = 0.80, 0.50, 0.40. It is shown, that the binary sub-system Ga-Li shows a strong exothermic behavior with a molar liquid mixing enthalpy of ΔmixH = −22.4 kJ·mol−1 at x(Li) = 0.58 (1081 K). In accordance with an even more negative molar mixing enthalpy of ΔmixH = −36.82 kJ·mol−1 at x(Li) = 0.7 (1081 K) in the binary sub-system Li-Sn, the ternary Ga-Li-Sn system is characterized by a strong exothermic behavior. Our experimental values for the binary Ga-Li system agree well with literature data and ΔmixH against composition was described by a Redlich-Kister polynomial. It is shown, that for the ternary Ga-Li-Sn system the extrapolation model of Toop is sufficient enough to describe the mixing enthalpy of the liquid phase. Moreover, our experimental ternary data were numerically fitted on the basis of an extended Redlich-Kister-Muggianu model which was designed for the excess energy of the substitutional-regular-solution model.