Calorimetric measurements of the Li–Zn system. Direct reaction method and mixing enthalpy

Highlights: • Calorimetric measurements of liquid Li–Zn alloys. • Integral enthalpies of mixing of liquid Li–Zn alloys at 814 K. • Enthalpy of formation of βLi₂Zn₃, βLi₂Zn₅ and βLiZn₄ phases. • Thermodynamic properties of liquid Li–Zn alloys. - Abstract: The formation enthalpy of the βLi₂Zn₃, βLi₂Zn₅ and βLiZn₄ intermetallic phases and the integral enthalpy of mixing of liquid Li–Zn alloys were measured with the use of two calorimetric techniques. The direct reaction calorimetric method was used for the determination of the formation enthalpy of the βLi₂Zn₃, βLi₂Zn₅ and βLiZn₄ intermetallic phases, and the obtained values equal: −16.7 ± 0.5 kJ/mol at., −19.0 ± 0.6 kJ/mol at., and −14.2 ± 0.6 kJ/mol at., respectively. The integral molar enthalpies of mixing for the Li–Zn liquid alloys were determined by means of drop calorimetry in three separate series at 814 K. The obtained experimental values are negative in the entire range of concentrations. The minimum of the integral enthalpy of mixing was observed for 0.3790 mole fraction of lithium and it equals −12.3 kJ/mol Based on the data of this study and those available in the literature, the interaction parameters of the Redlich–Kister equation for the liquid Li–Zn phase were calculated by the least square method.