Neutron Diffraction and Mössbauer Spectral Study of Nd₂Fe₁₆Ti and Its Nitride
The 295 K powder neutron diffraction patterns and the temperature dependence of the Mössbauer spectra of Nd2Fe17-xTix and Nd2Fe17-xTixNx have been measured. A Rietveld refinement of the neutron diffraction patterns yields the Nd2Fe16.32Ti0.68 and Nd2Fe16.32Ti0.68N2.7 stoichiometries for the two compounds and indicates that titanium occupies only the 6c crystallographic site and nitrogen only the 9e site in the rhombohedral Th2Zn17 structure. The insertion of interstitial nitrogen into Nd2Fe16.32Ti0.68 produces a 6.8% increase in the unit cell volume. The relative areas of the Mössbauer spectral components indicate that iron-iron, iron-titanium, and titanium-titanium 6c-6c dumbbell pairs exist in both of these materials. The magnetic hyperfine fields observed for the iron on the 6c site in the iron-titanium dumbbell pair in both compounds is substantially reduced from that found in Nd2Fe17 and Nd2Fe17N2.6 because of the titanium dumbbell near neighbor. For all the remaining hyperfine parameters there is a good correlation with those observed in Nd2Fe17 and Nd2Fe17N2.6. A linear increase is observed for the weighted average isomer shift with increasing unit cell volume for Nd2Fe17, Nd2Fe17N2.6, Nd2Fe16.32Ti0.68, and Nd2Fe16.32Ti0.68N2.7, because of the decreasing s-electron density at the iron-57 nucleus. © 1998 American Institute of Physics.
F. Grandjean et al., "Neutron Diffraction and Mössbauer Spectral Study of Nd₂Fe₁₆Ti and Its Nitride," Journal of Applied Physics, American Institute of Physics (AIP), Jan 1998.
The definitive version is available at http://dx.doi.org/10.1063/1.368317
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© 1998 American Institute of Physics (AIP), All rights reserved.