The effect of ternary additions on the hyperfine interaction parameters at Fe nuclei in the Fe50Al50 compound: First-principles calculations

Abstract

First-principles calculations using the linear augmented plane wave method (LAPW) within the framework of the density functional theory were performed to investigate the effect of the substitution of Fe atoms by transition elements (4d-T = Tc, Ru, Rh; 5d-T = Re, Os, Ir), in the concentration of 1.85 at.%, on the hyperfine interaction parameters at Fe nuclei in the Fe50Al50 compound. The results revealed that the ternary alloying additions lead to variations in the hyperfine interactions. Significant variations of the magnetic hyperfine field (Hhf) and of the isomer shift (IS) occur for Fe atoms nearest neighbors (nn) to T atom and depend upon the number of outer shell electrons (Ne) of the T atom. The larger changes in the Hhf of Fe nn were observed for 4d-T and 5d-T atoms with Ne = 7 and 8, while the changes of the IS arise by additions of T atoms with Ne = 8 and 9. The calculations results of the electric field gradient have shown variations that reflect a pronounced redistribution of charge over all Fe sites of the lattice. All the results point out a significant disturbance of the spatial distribution of the valence charge around Fe nuclei.