Thermodynamic assessment of the Ce-Rh system by the combination of ab-initio calculations and the CALPHAD approach

Abstract

The standard enthalpies of formation in this work have been measured calculated by First -principles calculations within DFT (density functional theory) for the metal compounds in the Ce-Rh system. Thermodynamic data and phase diagram information obtained from the literature were used as the input for a CALPHAD-type optimization and Thermo-Calc software of the Ce-Rh.The Ce-Rh phase diagram contains seven intermetallic compounds: Ce7Rh3, Ce5Rh3, Ce3Rh2, Ce5Rh4, CeRh, CeRh2 and CeRh3. All these phases were stoichiometric; The associated model concerning the phase equilibria, could accurately describe the full compositional range and the thermodynamic data input with CeRh as associate. The thermodynamic parameters of all intermetallic compounds were modeled by the Neumann-Kopp principle. The value of the temperature-dependent contributions to the individual Gibbs energies was used for all compounds. A fairly good agreement with all values of the enthalpies of formation calculated in this work using the VASP and data available in the literature. ultimately, a set of self-consistent thermodynamic parameters for the Ce-Rh system was obtained.