Thermodynamic assessment and experimental investigation of the Li–Sn system

The Li-Sn phase diagram was re-investigated using differential thermal analysis (DTA). A special thermal analysis technique was used to clarify the characters of the invariant reactions between the liquid, ^{Li17 Sn4} and ^{Li7 Sn2} phases and between the liquid, ^{Li7 Sn2} and ^{Li13 Sn5} phases. Using this technique, the eutectic reaction: L虠 ^{Li17 Sn4}+ ^{Li7 Sn2} and the peritectic reaction: L+ _Li7 ^Sn2虠 ^{Li13 Sn5} were confirmed. The enthalpy of formation of the ^{Li17 Sn4} phase was measured using high temperature solution calorimetry. A self-consistent thermodynamic description of the Li-Sn system was developed using the CALPHAD method. The liquid phase was described using the associate model, the ^{Li17 Sn4}, ^{Li13 Sn5}, ^{Li5 Sn2}, ^{Li7 Sn3}, LiSn and ^{Li2 Sn5} phases were modeled as stoichiometric compounds, and the ^{Li7 Sn2} phase was modeled to exhibit a homogeneity range at higher temperatures. Phase diagrams and property diagrams calculated using the new thermodynamic description for the Li-Sn system are in good agreement with the experimental data performed in this work and with literature data.