Ab initio determination of the (001) antiphase-boundary energy in the D0₂₂ Ni₃V compound

Abstract

The cohesive energies of L1₂, D0₂₂, D0₂₃ and selected one-dimensional (1D) long-period structures (LPSs) based on the L1₂ structure in the Ni-V system for the Ni₃V composition have been obtained by ab-initio calculations using the Vienna ab-initio simulation package. Relaxations, both external and internal with respect to the cell, are taken into account in the determination of the structural stability of the 1D LPSs. At each stage of the relaxation process the D0₂₂ structure is the ground state. The values of the (001) antiphase-boundary (APB) energies are obtained from the energy differences of 1D LPSs with respect to either L1₂ or D0₂₂, with stacking of at least three L1₂ cubes along the direction perpendicular to the APB. The energy effects in the 1D LPSs are described in the framework of an axial next-nearest neighbour Ising model. The values of the interaction parameters are obtained in the ideal, distorted and fully relaxed structures. The APB energies are also derived from these parameters. The results show that it is necessary to consider long-range interactions in order to obtain reliable values of the APB energies. The results show also the influence of the relaxation effects on the APB energies.