ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We have investigated the effect of substitution and nitrogenation on the hyperfine parameters in Gd2Fe17−x(Ga,Al)x (x=1–10) and Gd(Fe,Co)12−xMox(Ny) (x=1.5–3.0 and y≈1) by means of 155Gd Mössbauer spectroscopy. We have observed marked changes in the values of the electric field gradient Vzz, the effective Gd-hyperfine field, and isomer shift. Al substitution in Gd2Fe17 leads to a sign reversal of the electric field gradient. No sign reversal of Vzz has been observed in the Gd2Fe17−xGax compounds. The effective hyperfine fields of the Gd2Fe17−x(Ga,Al)x compounds are decreasing with increasing x, due to the reduction of the 6s electron polarization resulting from the decreasing Fe moments. The ultimate value of the isomer shift based on a simple model on chemical effects that would be reached for x=17 is 0.52 mm s−1 for Al and 0.64 mm s−1 for Ga substitution in Gd2Fe17, respectively. The electric field gradient of the GdFe12−xMox compounds were obtained for x=1.5 and x=3.0. Nitrogenation is shown to lead to a sign reversal of the 4f and Fe sublattice anisotropy. Mo substitution in GdCo12−xMox shows a decreasing negative value of Vzz with increasing Mo concentration x. The values ||Heff|| in GdCo12−xMox increase with increasing Mo concentration. This can be attributed to a different near neighbor Gd and 3d-metal contribution to the effective hyperfine field compared to those of GdFe12−xMox. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.361737
