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Cationic exchange in nanosized ZnFe2O4 spinel revealed by experimental and simulated near-edge absorption structure

S. J. Stewart·S. J. A. Figueroa·J. M. Ramallo-López·S. G. Marchetti·J. F. Bengoa·R. J. Prado·F. G. Requejo
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Abstract

The non-equilibrium cation site occupancy in nanosized zinc ferrites (6-13 nm) with different degree of inversion (0.2 to 0.4) was investigated using Fe and Zn K-edge x-ray absorption spectroscopy XANES and EXAFS, and magnetic measurements. The very good agreement between experimental and ab-initio calculations on the Zn K-edge XANES region clearly show the large Zn2+(A)--Zn2+[B] transference that takes place in addition to the well-identified Fe3+[B]--Fe3+(A) one, without altering the long-range structural order. XANES spectra features as a function of the spinel inversion were shown to depend on the configuration of the ligand shells surrounding the absorbing atom. This XANES approach provides a direct way to sense cationic inversion in these spinel compounds. We also demonstrated that a mechanical crystallization takes place on nanocrystalline spinel that causes an increase of both grain and magnetic sizes and, simultaneously, generates a significant augment of the inversion.

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S. J. Stewart, S. J. A. Figueroa, J. M. Ramallo-López, S. G. Marchetti, J. F. Bengoa, R. J. Prado, F. G. Requejo. 2006-11-21. Cationic exchange in nanosized ZnFe2O4 spinel revealed by experimental and simulated near-edge absorption structure. https://doi.org/10.1103/physrevb.75.073408

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