Cerium M-edge X-ray Absorption and an Iron L-edge Magnetic Circular Dichroism Study of the Ce₂Fe₁₇₋ₓMₓ Solid Solutions, Where M Is Al and Si
The cerium M-edge X-ray absorption spectra and the iron L-edge magnetic circular dichroism spectra of the Ce2Fe17-xMx solid solutions, where M is aluminum and silicon, were measured at room temperature. The cerium M-edge spectra was used to determine the variation in the valence of cerium in the solid solutions. The resulting values, which range from 3.20 in Ce2Fe16.8Si0.2 to 3.02 in Ce2Fe6Al11, decrease linearly with x in both series, but the decrease is twice as large in Ce2Fe17-xSix. Interestingly, the resulting valencies are quantitatively different from those determined using cerium L-edge X-ray absorption data, but the qualitative trends in the valence with metalloid substitution is the same using either the cerium L- or M-edge data. The cerium valencies also correlate linearly with the cerium Wigner-Seitz cell volumes, but with a positive slope for the silicon and a negative slope for the aluminum solid solutions. This difference results because of the more extensive cerium-silicon covalent bonding interaction in Ce2Fe17-xSix as compared to the cerium-aluminum interaction in Ce2Fe17-xAlx. The iron L-edge magnetic circular dichroism spectra indicate that a non-zero iron orbital moment is coupled parallel to the iron spin moment. The orbital moments range from 0.0 to 0.2 μB and reveal that the orbital moments are probably independent of x and are ca. 0.07 μB for both series of solid solutions. The cerium M-edge magnetic circular dichroism spectra reveal no dependence upon the relative orientation of the magnetization or the photon helicity, indicating that there is no 4f magnetic moment associated with cerium in these solid solutions.
F. Grandjean et al., "Cerium M-edge X-ray Absorption and an Iron L-edge Magnetic Circular Dichroism Study of the Ce₂Fe₁₇₋ₓMₓ Solid Solutions, Where M Is Al and Si," Solid State Communications, Elsevier, Jan 1999.
The definitive version is available at http://dx.doi.org/10.1016/S0038-1098(98)00623-1
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