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

摘要

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 C-p-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 electro-chemical equilibria in the Li-Si-system. (C) 2017 Elsevier Ltd.