Abstract
A thermodynamic study of the lithium‐tin system was made using galvanic cells of the type
over the temperature range from 360° to 590°C. The composition of the alloy was varied from pure tin to 86 a/o Li using the coulometric titration technique. Coulometric titration curves showed that six intermediate phases exist, with nominal stoichiometric compositions 
, 
, 
, 
, 
, and 
. At low lithium concentrations, the activity of lithium in molten lithium‐tin alloys follows Henry's law behavior. The partial and integral molar thermodynamic properties of the lithium‐tin system were evaluated as a function of composition from emf measurements at 415°C. The temperature dependence of the standard Gibbs free energies of formation for the six intermediate phases was also determined. The experimental results were used to map out parts of the phase diagram of the lithium‐tin system. The homogeneity ranges of the six solid phases are all quite narrow. The phase 
congruently melts at about 488°C and the phase 
peritectically decomposes at 500°C. These two phases form an eutectic mixture of 57 a/o Li at 470°C. The liquidus line on the tin‐rich side of the binary phase diagram was found to agree with data reported in literature.