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Reducción topotáctica de YBaCo2O5 y LaBaCo2O5: Co (I) plano cuadrado en un óxido extendido
James Seddon1, Emmanuelle Suard, Michael A Hayward
1Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom.
Journal of the American Chemical Society
|February 6, 2010
Resumen
La reducción topotáctica de los óxidos de cobalto YBaCo ((2) O ((5)) y LaBaCo ((2) O ((5)) produce estructuras deficientes en aniones. El orden y la identidad del catión en el sitio dirigen las redes de metales y oxígeno resultantes y los entornos de coordinación.
Área de la Ciencia:
- Química del estado sólido.
- Ciencia de los materiales ciencia de los materiales.
- Química inorgánica y inorgánica.
Sus antecedentes:
- La reducción topotáctica es un método clave para crear óxidos con deficiencia de aniones.
- La disposición de los cationes del sitio A en las fases REBaCo(2)O(5-x) influye en sus propiedades estructurales y magnéticas.
Objetivo del estudio:
- Investigar cómo el ordenamiento catiónico del sitio A y el ordenamiento de vacío aniónico directo de identidad en óxidos de cobalto reducidos topotáticamente.
- Para sintetizar y caracterizar nuevas estructuras de óxido de cobalto deficiente en aniones con entornos de coordinación inusuales.
Principales métodos:
- Reducción de bajas temperaturas utilizando NaH.
- Difracción de rayos X para el análisis estructural.
- Mediciones de la susceptibilidad magnética.
- Difracción de neutrones de temperatura variable. difracción de neutrones de temperatura variable. difracción de neutrones de temperatura variable. difracción de neutrones de temperatura variable.
Principales resultados:
- YBaCo{2O}{4.5} y LaBaCo{2O}{4.25) fueron sintetizados, exhibiendo estructuras ordenadas de vacantes aniónicas distintas.
- YBaCo(2)O(4.5) presenta unidades de CoO(5) y CoO(4), mientras que LaBaCo(2)O(4.25) incluye unidades planas cuadradas de CoO(5), CoO(4), y CoO(4).
- Ambos compuestos muestran ordenamiento antiferromagnético por debajo de 280 K y 325 K, respectivamente, con LaBaCo(2)O(4.25) mostrando evidencia de centros Co(I).
Conclusiones:
- La identidad y el orden de los cationes del sitio A (Y3+ y La3+) dictan las estructuras ordenadas de la vacante aniónica en estos óxidos de cobalto.
- Los cationes ordenados del sitio A proporcionan una ruta para controlar el ordenamiento de la vacante de aniones en la reducción topotáctica.
- Esta estrategia permite la preparación de nuevos marcos de metal-oxígeno con geometrías de coordinación de metales de transición únicas.
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