The heat capacity and entropy of the four lithium stannides Li17Sn4, Li7Sn2, Li13Sn5 and Li7Sn3 in the temperature range (2 to 865) K

This work presents the heat capacity of four lithium stannides Li17Sn4, Li7Sn2, Li13Sn5 and Li7Sn3 covering a temperature range from (2 to 865) K. Two different calorimeters depending on their specification were used. A calorimetric method based on a relaxation technique was applied in the low temperature region from (2 to 300) K and data between (300 to 865) K were measured with a DSC utilising the Cp-by-step method. The accuracy of the experimental data is better than ± 2% above 20 K and rises up to 20% below 20 K. The obtained data were split into appropriate temperature intervals and fitted to common heat capacity functions. The low temperature measurement permits the calculation of the standard entropy and entropy of formation as well as temperature coefficients of electronic and lattice contributions to the heat capacity. This study represents a significant improvement of the data basis for thermodynamic calculations (e.g. CALPHAD) and to the understanding of electrochemical equilibria in the Li-Sn-System.