Site occupancy behaviours of ternary elements (Zr, Mo, Cr) in the Laves phase of C15 NbCo₂: a first-principles study

Abstract

First-principles method based upon the density functional theory has been carried out to investigate the site occupancy behaviours of typical ternary elements Zr, Cr and Mo in the C15 NbCo₂ Laves phase. The calculated equilibrium lattice constant of the Nb₈Co₁₆ unit cell is in good agreement with the previous experimental results. The calculated results indicate that all the considered ternary elements show the preference to occupy the Co sites, and the site preference of these elements in the Laves phase is in the order of Cr, Mo and Zr. Mo and Cr atoms tend to participate in the formation of the Laves phase, generating Nb₇MoCo₁₆, Nb₈Co₁₅Mo and Nb₈Co₁₅Cr, respectively. Zr atoms are not prone to concentrate in the Laves phase. The partial density of states was also calculated to investigate how atoms interact, and the charge density difference is analysed to reflect the bonding characteristics.

Keywords:

• First-principles
• Laves phase
• ternary elements
• site occupancy

Disclosure statement

No potential conflict of interest was reported by the authors.