The Phase Stability, Thermodynamics Properties and Electronic Structures of L1₂-Type Al₃Sc and Al₃Y under High Pressures

The phase stability, thermodynamics properties and electronic structures of L1₂-Al₃Sc and Al₃Y compounds under pressure up to 40 GPa are investigated by using first-principles within a local density approximation. The results of formation energies show that Al₃Sc is more stable than Al₃Y and the stability of Al₃Sc will be better with the increasing pressure. The Gibbs free energy, heat capacity, Debye temperature and thermal expansion coefficient are also investigated. The decreasing density of states at the Fermi level and the strengthening Sc/Y-d orbital hybridization with Al (s, p) under high pressure lead to the observed increase of the structural stability for L1₂-Al₃Sc and Al₃Y under pressures.