First-principles investigation of the stability and stabilization mechanism of Ni2Zn11 γ brasses under high pressure

Abstract

The γ brasses, a family of structurally complex intermetallic compounds containing 52 atoms in the cubic unit cell, attract increasing interest due to their highly ordered but unusual symmetry structure. To investigate their stability and performance under high pressure, we have extensively studied the elastic, thermodynamic and electronic properties as well as their dependences on pressures up to 71GPa by first-principles calculations using one γ brasses phase (N2Zn11) as an example. We found that Ni2Zn11 remains energetically, mechanically and dynamically stable under the present studied pressure range. Further analysis on the electronic structure of Ni2Zn11 unravels that under various pressures, the pseudogap at the Fermi level which reduces the electronic energy of the system accounts for the stability of γ brasses, i.e., the well-known stabilization mechanism still holds at high pressure. Besides, various thermodynamic quantities of Ni2Zn11 under high pressure were systematically calculated and analyzed. Our present results extend the knowledge of the stabilization mechanism and performance of γ brasses to a high pressure condition.