Thermodynamic Properties of MgSc and AlSc from First-Principles Phonon Calculations

The thermodynamic properties of intermetallic compounds MgSc and AlSc with CsCl-type B2 structure have been studied by performing density functional theory and density functional perturbation theory within the quasi-harmonic approximation in comparison with NiAl. The linear thermal expansion of the lattice, coefficients of thermal expansion, isothermal bulk modulus, phonon dispersions, phonon density of states, and specific heat capacities at constant volume and constant pressure have been obtained. Comparisons have been made with available experimental data and the results of previous calculations, and good agreement has been obtained. Our results show that the thermal expansion of MgSc is larger than that of AlSc.