Thermodynamic assessment of the Ga–La and Ga–Pr systems supported by ab-initio calculations

Abstract

Ab-initio calculations within density functional theory (DFT) were used to calculate the enthalpies of formation of the binary intermetallics in the Ga–La and Ga–Pr systems. The thermodynamic data and the phase diagram of these systems have been critically assessed according to the Calphad technique. The primary solid solutions in the two systems were modeled with Redlich–Kister polynomial, while the associate model was used to describe the short-range ordering behavior of the liquid phase.The intermetallics compounds Ga6La, Ga4La, Ga2La, GaLa, Ga3La5, GaLa3, Ga6Pr, Ga2Pr, GaPr, Ga3Pr5 and GaPr2 in addition to the suspected compound Ga3Pr are taken into consideration in this optimization. The calculated enthalpies of formation using the VASP code are used in the optimization of the Ga–La and Ga–Pr phase diagrams which agrees well with the experimental data.