Lattice vibrational properties of Al2X (X = Sc, Y) from density functional theory calculations

The phonon dispersion curves of the C15-type of Al2Sc and Al2Y compounds are investigated, using density functional theory within the generalized gradient approximation (GGA), based on the “direct method”. The obtained results show that both compounds are dynamically stable. The temperature dependence of the various thermodynamical quantities such as internal energy, free energy, entropy, and heat capacity are also predicted under the harmonic approximation, and the observed trends are discussed in detail.