Formation enthalpy of Ga-Li intermetallic phases. Experiment vs. calculations

The solution calorimetric method was applied to determine the heat of solution of liquid gallium in the liquid tin and the standard enthalpies of formation of the Ga64.3Li35.7 alloy (composition corresponds to the Ga9Li5 intermetallic phase), and GaLi, Ga2Li3 intermetallic phases. These alloys were prepared from pure, metallic Ga and Li, which were melted in a glove-box filled with high purity argon with a very low concentration of impurities. All experiments were performed with the use of a Setaram MHTC 96 Line evo calorimeter. The heat of solution (limiting partial enthalpy of solution) of gallium in a Sn-bath shows a temperature dependence. The standard enthalpies of formation of the Ga64.3Li35.7 (Ga9Li5), GaLi and Ga2Li3 intermetallic phases, were measured at 723 K; the obtained values were −26.7 ± 1.4, −33.5 ± 2.0, and −31.1 ± 2.0 kJ/mol at., respectively. First principles calculations were performed to determine the enthalpies of formation of each compound. It was found that the latter are in much better agreement with the experimental data than those obtained with the Miedema model.