Magnetic Hyperfine Interactions and Electric Quadrupolar Coupling in Alloys of Iron with the Alpha-Manganese Structure

The Mössbauer technique has been used to investigate the magnetic hyperfine field and electric quadrupolar coupling at Fe nuclei in $\chi$-phase ternary alloys and in antiferromagnetic MnFe alloys having the $\alpha$-Mn structure. Alloys with 5, 10, 20, and 30 at.% Fe in $\alpha$-Mn and the $\chi$-phase alloys $\chi \left({\mathrm{V}}_{30}{\mathrm{Si}}_{20}{\mathrm{Fe}}_{50}\right)$, $\chi \left({\mathrm{Ti}}_{17}{\mathrm{Cr}}_{24}{\mathrm{Fe}}_{59}\right)$, and $\chi \left({\mathrm{Mo}}_{17}{\mathrm{Cr}}_{21}{\mathrm{Fe}}_{62}\right)$ were examined at 4, 77, and 300°K. The data are consistent with the assumption that of the four available sets of sites, Fe occupies only sites III and IV. The Fe atoms appear to have no aligned $3d$ moment. For FeMn alloys the fact that the spectra at a given temperature are nearly independent of composition indicates that (1) the ratio between the Fe populations of the two sites is the same for each composition, and (2) the isomer shift, the magnetic field, and the electric-field gradient at an Fe site are not sensitive to whether neighboring atoms are Fe or Mn. A different Debye temperature is associated with Fe at each site.