A thermodynamic description of the Ge–Sr system acquired via a hybrid approach of CALPHAD and first-principles calculations

Abstract

The Ge–Sr system is investigated via a hybrid approach of CALPHAD and first-principles calculations. The experimental phase diagram and thermodynamic data available in the literature are critically reviewed and assessed by using thermodynamic models for the Gibbs energies of the individual phases. The enthalpies of formation for Ge 2Sr, GeSr, Ge 3Sr 5, and GeSr 2 are computed via first-principles calculations. These first-principles generated enthalpies of formation are used as key “experimental data”, which are needed for the CALPHAD approach in order to provide thermodynamic parameters with sound physical meaning. A consistent thermodynamic data set for the Ge–Sr system is obtained by using reliable literature data and the enthalpies of formation computed with the first-principles method. Comparisons between the calculated and measured phase diagram and thermodynamic quantities show that the accurate experimental information is satisfactorily accounted for by the present thermodynamic description.