The elastic constants for Fe3AlX (X=B, C and N) with anti-perovskite structure

Abstract

The total energy and bulk properties of Fe3AlX (X=B, C and N) with anti-perovskite structure at T=0 K were calculated by using the projector augmented-wave (PAW) approach within generalized gradient approximation (GGA) and local density approximation (LDA). The lattice constant, bulk modulus and its pressure derivative, elastic constants, shear modulus, Poisson's ratio and Debye temperature both in paramagnetic and ferromagnetic states for Fe3AlX have been calculated. The calculations indicate that the ground states of Fe3AlB and Fe3AlC are ferromagnetic, while for Fe3AlN its ground state is paramagnetic. The calculated total energy within LDA is lower than that within GGA. The calculated lattice constant of Fe3AlC within GGA is in good agreement with experimental value, and this indicates that the calculations from GGA are more accurate than those from LDA. The calculated elastic constants and bulk moduli agree with other theoretical results available. The average magnetic moments of Fe in Fe3AlX (X=B, C and N) are 1.483, 1.103 and 0.0 μB (GGA), or 1.300, 0.401 and 0.0 μB (LDA), respectively.