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De amarillo a negro: cambios dramáticos entre los molibdatos de cerio (IV) y plutonio (IV)
Justin N Cross1, Patrick M Duncan, Eric M Villa
1Department of Chemistry and Biochemistry, University of Notre Dame, 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Journal of the American Chemical Society
|January 31, 2013
Resumen
La síntesis hidrotermal produjo estructuras distintas de molibdato de cerio y plutonio. El compuesto de plutonio, CsPu(3)Mo(6)O(24)(H(2)O), exhibe un color semiconductor negro-rojo debido a los estados de oxidación mixtos de Mo.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Ciencia de los materiales Ciencia de los materiales.
- Química del estado sólido.
Sus antecedentes:
- Las reacciones hidrotermales son versátiles para sintetizar nuevos compuestos inorgánicos.
- Las químicas del cerio y el plutonio, particularmente con los óxidos de molibdeno, presentan retos y oportunidades únicas.
- Comprender las propiedades estructurales y electrónicas de las tierras raras y los compuestos de actinuros es crucial para las aplicaciones de materiales.
Objetivo del estudio:
- Para investigar las reacciones hidrotermales comparativas de los cloruros de cerio y plutonio con trióxido de molibdeno y carbonato de cesio.
- Caracterizar las estructuras cristalinas resultantes y sus propiedades.
- Para dilucidar los factores que contribuyen a los colores distintos y el comportamiento semiconductor de los compuestos sintetizados.
Principales métodos:
- Reacciones de síntesis hidrotermales.
- Difracción de rayos X monocristalino para la determinación estructural.
- Espectroscopia de la estructura de absorción de rayos X cercana al borde (XANES) para el análisis del estado de oxidación.
Principales resultados:
- Se sintetizaron dos compuestos distintos: Ce ((3) Mo ((6) O ((24) (((H(2) O) ((4) (placas amarillas) y CsPu ((3) Mo ((6) O)) (placas semiconductoras de color rojo negro).
- Ambos compuestos comparten estructuras de canal similares, pero difieren en los ocupantes del canal (agua frente a Cs +).
- XANES confirmó el plutonio tetravalente y reveló un estado de oxidación ambiguo de Mo (Mo(V) / Mo(VI)) en el compuesto de plutonio, lo que contribuye a su color.
Conclusiones:
- La presencia de Cs+ en los canales del compuesto de plutonio, junto con estados de oxidación mixtos de Mo, conduce a sus propiedades semiconductoras y de color rojo-negro.
- La topología estructural se conserva, pero la ocupación catiónica influye significativamente en las propiedades del material.
- El estudio destaca la reactividad matizada del cerio y el plutonio bajo condiciones hidrotermales.
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