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Transición ferroeléctrica de desorden y orden en el marco de formato metálico de [NH4][Zn(HCOO) [3]
Guan-Cheng Xu1, Xiao-Ming Ma, Li Zhang
1Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
Journal of the American Chemical Society
|June 30, 2010
Resumen
Un nuevo marco de formato metálico exhibe una transición de fase paraeléctrica-ferroeléctrica conmutable. Esta transición es impulsada por el ordenamiento de cationes de amonio dentro de la estructura quiral tridimensional a 191 K.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química del estado sólido.
- La cristalografía es una técnica de cristalografía.
Sus antecedentes:
- Las estructuras metal-orgánicas (MOF) ofrecen propiedades sintonizables para diversas aplicaciones.
- Los MOF quirales son de interés para los procesos enantioselectivos y los nuevos fenómenos físicos.
- Los cationes de amonio pueden influir en las transiciones estructurales en los materiales marco.
Objetivo del estudio:
- Para investigar el comportamiento de transición de fase del marco tridimensional de formato de metal quiral [NH(4) ][Zn(HCOO) ((3) ].
- Comprender el papel de la dinámica de los cationes de amonio en el desencadenamiento de la transición.
- Caracterizar las propiedades ferroeléctricas derivadas de los cambios estructurales.
Principales métodos:
- Difracción de rayos X monocristalino para determinar las estructuras cristalinas.
- Calorimetría de barrido diferencial (DSC) para el análisis térmico.
- Espectroscopia dieléctrica para sondear las propiedades ferroeléctricas.
Principales resultados:
- El compuesto [NH(4)][Zn(HCOO)(3)] exhibe una transición de fase a 191 K.
- La transición está asociada con una reorganización de desorden-orden de los cationes de amonio (NH ((4) ((+)).
- Se observó evidencia de una transición paraeléctrica-ferroeléctrica, vinculada al ordenamiento catiónico.
Conclusiones:
- El marco de formato metálico demuestra una transición de fase paraeléctrica-ferroeléctrica inducida por la temperatura.
- El ordenamiento de los cationes de amonio es el mecanismo clave que impulsa la ferroelectricidad en este material.
- Este estudio pone de relieve el potencial de los compuestos de marco quiral para propiedades electrónicas conmutables.
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