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, Li 17 Sn 4 and Li 7 Sn 2 phases and between the liquid, Li 7 Sn 2 and Li 13 Sn 5 phases. Using this technique, the eutectic reaction: L ↔ Li 17 Sn 4 + Li 7 Sn 2 and the peritectic reaction: L + Li 7 Sn 2 ↔ Li 13 Sn 5 were confirmed. The enthalpy of formation of the Li 17 Sn 4 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 Li 17 Sn 4 , Li 13 Sn 5 , Li 5 Sn 2 , Li 7 Sn 3 , LiSn and Li 2 Sn 5 phases were modeled as stoichiometric compounds, and the Li 7 Sn 2 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.