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Iones de cobalto de alto espín ((II) en coordinación cuadrada plana: estructuras y magnetismo de los oxisulfuros
Catherine F Smura1, Dinah R Parker, Mohamed Zbiri
1Department of Chemistry, University of Oxford, Oxford, UK.
Journal of the American Chemical Society
|February 10, 2011
Resumen
El estudio revela que los oxicalcogenuros en capas exhiben un ordenamiento antiferromagnético, con el momento magnético ordenado aumentando con el contenido de Ba debido a la elongación tetragonal de los poliedros de coordinación de cobalto. Esta elongación mejora los componentes orbitales no extinguidos en los iones cobalto (II).
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física del estado sólido Física del estado sólido
- Química Inorgánica La Química Inorgánica es la química inorgánica.
Sus antecedentes:
- Se investigan las propiedades magnéticas de los oxicalcogenuros en capas (Sr(1-x) Ba(x))(2)CoO(2)Cu(2)S(2).
- Los iones de cobalto (II) en estos compuestos están coordinados por óxidos y sulfuros, formando octaedros alargados tetragonalmente.
Objetivo del estudio:
- Determine las estructuras antiferromagnéticas de (Sr(1-x) Ba(x))(2)CoO(2)Cu(2)S(2) utilizando la difracción de neutrones en polvo.
- Investigar la correlación entre los parámetros estructurales, en particular el alargamiento tetragonal, y las propiedades magnéticas de los iones cobalto.
Principales métodos:
- Se empleó difracción de neutrones en polvo para determinar las estructuras cristalina y magnética.
- Se realizaron cálculos ab initio para apoyar las observaciones experimentales.
Principales resultados:
- Se observó un ordenamiento antiferromagnético, con el vecino más cercano cobalto (II) momentos de acoplamiento antiferromagnético dentro de los planos CoO (II).
- El momento magnético ordenado del cobalto ((II) aumenta con el contenido de Ba, en correlación con el alargamiento tetragonal del poliedro CoO ((4) S ((2).
- La deficiencia de cobre, inducida por la exposición al aire húmedo, conduce a una disminución en el momento magnético ordenado.
Conclusiones:
- El alargamiento tetragonal del entorno de coordinación del cobalto influye significativamente en las propiedades magnéticas, particularmente en el componente orbital no extinguido.
- La distorsión magnetostrictiva observada por debajo de la temperatura de Néel está vinculada a la magnitud del momento magnético ordenado.
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