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Dinámica de protones y ferroelectricidad a temperatura ambiente en sales aniladas con una esponja de protones
Sachio Horiuchi1, Reiji Kumai, Yusuke Tokunaga
1Correlated Electron Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8562, Japan. s-horiuchi@aist.go.jp
Journal of the American Chemical Society
|September 11, 2008
Resumen
La ferroelectricidad y la dinámica de transferencia de protones se lograron utilizando 2,3,5,6-tetra(2'-piridil) pirazina (TPPZ) y ácidos anílicos. Este estudio revela las transiciones de fase y la ferroelectricidad a temperatura ambiente en nuevas estructuras cristalinas.
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:
- Los materiales ferroeléctricos son cruciales para los dispositivos electrónicos.
- La dinámica de transferencia de protones juega un papel clave en las propiedades de los materiales.
- El diseño de nuevos ferroeléctricos con propiedades sintonizables sigue siendo un desafío.
Objetivo del estudio:
- Investigar la ferroelectricidad y la dinámica de transferencia de protones en nuevos materiales.
- Para explorar las relaciones estructura-propiedades en sales de ácido anílico TPPZ.
- Comprender el mecanismo de las transiciones de fase ferroeléctricas.
Principales métodos:
- Mediciones dieléctricas para identificar las transiciones de fase.
- Difracción de rayos X sincrotrón para estudiar la estructura cristalina y la dinámica de los protones.
- Estudios de deuteración para confirmar la participación de los protones.
Principales resultados:
- Las transiciones de fase observadas a 334 K (Hba) y 172 K (Hca).
- Ferroelectricidad a temperatura ambiente evidenciada por la inversión de la polarización y la piroelectricidad.
- Dinámica de protones identificada en enlaces intramoleculares N-H-N y dimeros cíclicos.
- Los dímeros desordenados exhiben transferencia de doble protón por encima de T (c), ordenando en la fase ferroeléctrica.
- La dicatión TPPZ actúa como una esponja de protones, con la localización de protones impulsando la ferroelectricidad.
Conclusiones:
- La combinación de TPPZ y ácidos anílicos produce materiales ferroeléctricos con características dinámicas de transferencia de protones.
- El ordenamiento y la localización de protones dentro de la dicción TPPZ y los dímeros de ácido anílico son responsables de la ferroelectricidad observada.
- Estos hallazgos ofrecen información sobre el diseño de nuevos materiales ferroeléctricos basados en protones.
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