The heat capacity and entropy of the metastable lithium silicide Li15Si4 in the temperature range (2 to 615) K

- High quality experimental heat capacity data of the metastable lithium silicide Li15Si4 is reported.
- To cover the broad temperature range from (2 to 665) K, two different calorimeters were applied.
- The ball milled sample was characterized by XRD, chemical and thermal analysis.
- Supply of the polynomial heat capacity function for four appropriate temperature intervals.
- Computation of the standard entropy and entropy of formation.

This contribution presents the heat capacity of metastable Li15Si4 as a function of temperature in a range from (2 to 615) K. The measurements were performed using two different calorimeters depending on their specification. In the low temperature region from (2 to 300) K a calorimetric method based on a relaxation technique was used, whereas for the high temperature region from (300 to 615) K, DSC measurements applying the Cp-by-step method were carried out. The experimental data are given with an accuracy better than ±2% above 5 K and up to 9% below 5 K. The measurement at low temperatures allow the calculation of the standard entropy and entropy of formation as well as temperature coefficients of electronic and lattice contributions to the heat capacity. The results represent a significant contribution to the data basis for thermodynamic calculations (e.g. CALPHAD) and to the understanding of electrochemical equilibria in the Li-Si-system.