Electronic, magnetic and elastic properties of ε-phases Fe3X(X=B, C, N) from density-functional theory calculations

Abstract: First principles calculations have been performed for ε-phases Fe3X(X=B/C/N) with hexagonal close-packed Fe sublattices. The calculated equilibrium structural parameters of ε-Fe3C and ε-Fe3N are in agreement with experimental results. The crystal structure of the ε-Fe3B is predicted. In the view of the formation energy, the phase stabilities grow up from ε-Fe3B, θ-Fe3N, ε-Fe3C, θ-Fe3C, θ-Fe3B to ε-Fe3N. The bonding nature in ε-Fe3X (X=B/C/N) is described as a complex mixture of covalent, ionic and metallic characters. The average magnetic moments (Ms) of the ε-Fe3B, ε-Fe3C and ε-Fe3N are 1.53, 1.61 and 1.66μB/atom, respectively. The Ms of Fe are 2.17, 2.23 and 2.25μB in ε-Fe3B, ε-Fe3C and ε-Fe3N, respectively. The Ms of B/C/N are −0.39/−0.26/−0.08μB.The Debye temperatures of ε-Fe3X (X=B/C/N) are predicted as 427, 565 and 555K. [Copyright &y& Elsevier]