Dear Respected RG experts
Usually we determine cation distribution of spinel ferrites by different methods and used for understanding magnetic properties. My question is that, is it possible to have a reverse view, that is, by studying the magnetic properties (MH curve), can we get an estimation of cation distribution in spinel ferrites?
If yes, how?
Your kind views are most welcome.
With best regards
Chitra Devi,
Question related to your topic on ResearchGate (See the answers):
https://www.researchgate.net/post/How_do_you_calculate_cation_distribution_in_spinal_ferrite
Have also look on the following articles - may be useful
Study of cation distributions in spinel ferrites MxMn1-xFe2O4 (M=Zn, Mg, Al)
http://aip.scitation.org/doi/full/10.1063/1.4966253
Cation distributions estimated using the magnetic moments of the spinel ferrites Co1−xCrxFe2O4 at 10 K
http://iopscience.iop.org/article/10.1088/1674-1056/23/10/107503/meta
Regards
Thank you so much Sir for the kind response and sources.
Best regards
Thank you so much Dr Behzad for the valuable answers and suggestions.
With best regards
The question is quite simple, but the answer is rather complicated. First of all, you must EXACTLY know the chemical composition, i.e. the relative concentrations of all cationic elements and preferably also the oxygen stoichiometry. Further you must know the spontaneous magnetic moment of the formula unit, preferably at 0 K. The necessary condition for any quantitative conclusions about the distribution of cations over the (A - tetrahedral) and [B - octahedral] sites in the spinel lattice is their STRICT antiparallel orientation (i.e. no spin canting in the sublattice or between the sublattices).
Even then the sensitivity of the resulting moment on the distribution depends on the individual moments of the relevant cations that interchange their position between (A) and [B]. If the difference of the moments (both theoretical and experimental) of these ions is either zero (Fe3+ and Mn2+)or relatively small (Fe 3+ and Co2+), the effect of transferring these cations between sublattices is relatively weak. On the other hand if we change the position of "nonmagnetic" ion as Zn2+ for e.g. Fe3+, the resulting moment is rather sensitive to this change and the determination of the distribution of these ions is much more reliable.
And a remark en passant : Mössbauer spectroscopy is usually used just for the determination of the ditribution of Fe ions and very rarely, if at all, for other elements. If the spinel contains more than one element besida Fe, the information from Mössbauer spectra is only partial and must be completed by some other one.
Thank you so much Dr Karel for the detail explanation highlighting the complication which may arise due to estimation of stoichiometry, spin canting, cations having similar magnetic moments etc. Thanks again for sharing the important remarks
With best regards
Chitra
The distribution of cation distribution in magnetic oxides / ferrites can be found using XRD pattern by taking the relative intensity of the peaks of even sum of Miller Indices, h+k+l=4n, and 4n+2 viz, (220), (222) and (422) peaks. The intensities of planes (220) and (422) are sensitive to tetrahedral sites atoms while 4n+2 (222) gives Octahedral site positions. Therefore, the ratio I220/I222 , I422/I222 are an indication of the A and B sites occupation.
Ihkl = |F|2 P Lp
Another way of distribution was proposed in case of RE substituted cobalt ferrite theoretically using XRD pattern was discussed in '
Structural, morphological, magnetic properties and cation distribution of Ce and Sm co-substituted nano crystalline cobalt ferrite' https://doi.org/10.1016/j.matchemphys.2018.01.050 .
Regards
Thank you so much Dr Syed for the detail calculations using xrd data and the relevant source.
Sir, please also add reason for choosing sum of the indices as 4n and 4n+2 as it not explained clearly in most reported articles (to my knowledge). Or Please add relevant source. Thanks again for sharing these important informations.
With best regards
You might be useful if you have a look at this link
Article Correlating structural, magnetic, and luminescence propertie...
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