First-principles investigation of structural stability, mechanical and thermodynamic properties of Pt3Zr5 compounds

Abstract

Pt–Zr compounds are promising high-temperature structural materials due to the high melting point, high strength and excellent oxidation resistance etc. However, the correlation between structure and the related properties of Pt3Zr5 is entirely unclear. Here, we apply the first-principles calculations to study the structural stability, mechanical and thermodynamic properties of Pt3Zr5. Four structures: hexagonal (P63/mcm), tetragonal (I4/mcm), orthorhombic (Pbam) and orthorhombic (Cmcm) are considered. The calculated results show that the four Pt3Zr5 structures are thermodynamically stable at the ground state. In particular, the hexagonal (P63/mcm) phase is more thermodynamically stable than the other three structures. The calculated elastic modulus shows that the tetragonal (I4/mcm) Pt3Zr5 structure has stronger bulk deformation resistance in comparison to the other three structures. However, the hexagonal structure (P63/mcm) has stronger shear deformation resistance and higher elastic stiffness in comparison to the other structures. Naturally, the high mechanical properties of Pt3Zr5 are attributed to the strong cohesive force between Pt layer and the Zr layer. Finally, it is found the calculated Debye temperature of the hexagonal (P63/mcm) is 265.0 K, which is larger than the other structures.