The stability and properties of the PtFe2 Laves phases

Abstract

The structural stability of PtFe2 Laves phase with cubic and hexagonal structures has been investigated with the help of the first-principles methods, followed by targeted calculations of electronic, magnetic, lattice-dynamics and mechanical properties. The formation enthalpies of different magnetic configurations are calculated and their ferromagnetic (FM) states are found to be thermodynamically stable. However, there is strong competition for the FM states of the three structures, although the cubic C15 structure has the lowest energy. These FM states are dynamically stable owing to the spontaneous magnetization. The total magnetic moments of the FM state for these three structures are close to each other at 0 GPa, and the spin-polarized electronic DOS is investigated to promote insight into the magnetic properties. The elastic constants and modulus show that all three structures with FM state are mechanically stable, and the hexagonal C14 structure has the largest bulk modulus, but its shear modulus and Young's modulus are the lowest. Finally, the elastic anisotropy was quantified by several anisotropy indexes. The results reported here reveal that the anisotropy is in a sequence of C15 > C14 > C36.