Cationic exchange in nanosized ZnFe₂O₄ spinel revealed by experimental and simulated near-edge absorption structure
The nonequilibrium 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 near edge spectroscopy (XANES) and extended x-ray absorption fine structure, and magnetic measurements. The...
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| Autores principales: | , , , , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
2007
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/126026 |
| Aporte de: |
| Sumario: | The nonequilibrium 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 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 ) → 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 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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