The Li-Sb phase diagram part II: Calorimetry and thermodynamic assessment

Abstract

In this work, drop calorimetry measurements in the Li-Sb system were performed with different starting compositions to determine the enthalpies of mixing as well as liquidus compositions. By adding Sb into a Li bath at 979 K and 1080 K, the liquidus compositions were determined to lie between 0.5 at.% and 1.5 at.% at 979 K and between 1.5 at.% and 2.5 at.% at 1080 K. Furthermore, the limiting partial molar enthalpy of mixing of Li in Sb is −89.5 and −88 kJmol−1at 929 and 979 K, respectively. Likewise, the limiting partial enthalpy of mixing of Sb in Li is −238 kJmol−1at 1080 K. Based on our measurements, the enthalpy of formation for Li3Sb at 979 K was determined to be −76.5 kJmol−1 with respect to the pure solid components. Simultaneously, a thermodynamic description of the Li-Sb system was developed using the CALPHAD approach for the first time. Phase diagram information was taken from Part 1 of this publication, and all other phase diagram, thermochemical, and electrochemical data from the literature were taken into account. The thermodynamic calculations satisfactorily reproduced phase diagram data, enthalpy of mixing, enthalpy of formation and e.m.f. data.