Cationic exchange in nanosized ZnFe2O4 spinel revealed by experimental and simulated

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.

Physical Review B

American Pysical Society

Año: 2007 vol. 75 p. 734081 - 734084

1550-235X

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 spectroscopy
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 spectroscopy
0.2 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.