Structural and hyperfine characterization of σ-phase Fe–Mo alloys

A series of nine samples of σ-Fe100−xMox with 44 ≤ x ≤ 57 were synthesized by a sintering method. The samples were investigated experimentally and theoretically. Using X-ray diffraction techniques structural parameters such as lattice constants, atomic positions within the unit cell and populations of atoms over five different sublattices were determined. An information on charge-densities and electric field gradients at particular lattice sites was obtained by application of the Korringa–Kohn–Rostoker (KKR) method for electronic structure calculations. Hyperfine quantities calculated with KKR were successfully applied to analyze Mössbauer spectra measured at room temperature.

► Lattice parameters a and c linearly increase with the Mo content, c/a = 0.52233.
► The sites A and D are 100% occupied by Fe atoms.
► The sites B, C and E are populated by both types of atoms.
► The average isomer shift weakly decreases with Mo-concentration.
► The calculated quadrupole splittings are characteristic of a given sublattice.