Thermodynamic assessment of the Ba-La-S and Ga-La-S systems

TL;DR

This study provides the first thermodynamic assessment of the Ba-La-S and Ga-La-S systems using CALPHAD, combining experimental data, thermodynamic modeling, and ab initio calculations to accurately predict phase diagrams.

Contribution

It introduces a comprehensive thermodynamic assessment of these systems, integrating experimental data with ab initio calculations for the first time.

Findings

Good agreement with experimental phase diagrams

Thermodynamic properties accurately modeled

Liquid phase short-range ordering described

Abstract

This paper presents the first thermodynamic assessment of binary and pseudo-binary phase diagrams in the Ba--La--S and Ga--La--S systems by means of the CALPHAD method. Experimental phase diagram equilibrium data and thermodynamic properties available from the literature were critically reviewed and assessed using thermodynamic models for the Gibbs energies of individual phases. The associated solution model was used to describe the short-range ordering behavior of the liquid phases. To supplement the limited experimental data reported in the literature, ab initio molecular dynamics calculations were employed to derive mixing enthalpies of the liquid phases in the binary subsystems. The resulting phase diagrams and calculated thermodynamic properties show good agreement with available literature within the investigated compositional ranges of binary and pseudo-binary systems.