CINDECA   05422
CENTRO DE INVESTIGACION Y DESARROLLO EN CIENCIAS APLICADAS "DR. JORGE J. RONCO"
Unidad Ejecutora - UE
artículos
Título:
Cationic exchange in nanosized ZnFe2O4 spinel revealed by experimental and simulated
Autor/es:
S. J. STEWART, S. J. A. FIGUEROA, J. M. RAMALLO L¨®PEZ, S. G. MARCHETTI, J. F. BENGOA, R. J. PRADO, AND F. G. REQUEJO.
Revista:
Physical Review B
Editorial:
American Pysical Society
Referencias:
Año: 2007 vol. 75 p. 734081 - 734081
ISSN:
1550-235X
Resumen:
The nonequilibrium cation site occupancy in nanosized zinc ferrites 6¨C13 nm with different degree of inversion 0.2 to 0.4 was investigated using Fe and Zn K-edge x-ray absorption near edge spectroscopy6¨C13 nm with different degree of inversion 0.2 to 0.4 was investigated using Fe and Zn K-edge x-ray absorption near edge spectroscopy0.2 to 0.4 was investigated using Fe and Zn K-edge x-ray absorption near edge spectroscopy XANES and extended x-ray absorption fine structure, and magnetic measurements. The very good agreement between experimental and ab initio calculations on the Zn K-edge XANES region clearly shows the large Zn2+A¡úZn2+B transference that takes place in addition to the well-identified Fe3+B¡úFe3+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 Zn-containing spinel ferrites. 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.XANES and extended x-ray absorption fine structure, and magnetic measurements. The very good agreement between experimental and ab initio calculations on the Zn K-edge XANES region clearly shows the large Zn2+A¡úZn2+B transference that takes place in addition to the well-identified Fe3+B¡úFe3+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 Zn-containing spinel ferrites. 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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