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El hermanamiento múltiple dependiente del tamaño en superredes nanocristalinas
Sara M Rupich1, Elena V Shevchenko, Maryna I Bodnarchuk
1Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA.
Journal of the American Chemical Society
|December 9, 2009
Resumen
El tamaño de las superredes de nanocristales de sulfuro de plomo (PbS) influye en su estructura. Los nanocristales de PbS más grandes forman superredes gemelas múltiples con simetrías únicas, mientras que los más pequeños no lo hacen.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Nanotecnología La nanotecnología es la nanotecnología.
- La cristalografía es una técnica de cristalografía.
Sus antecedentes:
- Los nanocristales coloidales se autoensamblan en superredes ordenadas.
- La morfología y la simetría de estas superredes son cruciales para sus propiedades.
- La comprensión de los factores que controlan la formación de superredes es clave para el diseño de materiales.
Objetivo del estudio:
- Investigar la influencia del tamaño de los nanocristales en la morfología de las superretillas de sulfuro de plomo (PbS).
- Aclarar los mecanismos detrás de los cambios estructurales dependientes del tamaño observados.
- Explorar las implicaciones para el diseño de nuevos materiales con propiedades sintonizables.
Principales métodos:
- Síntesis de nanocristales de PbS monodispersos de diferentes tamaños (<4 nm y >7 nm).
- El autoensamblaje de los nanocristales de PbS en superrías.
- Caracterización de la morfología y simetría de la superretícula utilizando microscopía electrónica y técnicas de difracción.
Principales resultados:
- Las superredes formadas a partir de grandes nanocristales de PbS (>7 nm) exhibieron múltiples estructuras cúbicas centradas en la cara gemelas con simetría decaédrica e icosaédrica.
- Estas grandes superredes de nanocristales exhibían elementos de simetría de cinco veces prohibidos cristalográficamente debido a gemelos múltiples.
- Las superredes compuestas de pequeños nanocristales de PbS (<4 nm) no mostraron ningún hermanamiento.
- Se encontró que la energía de hermanamiento es fuertemente dependiente del tamaño, disminuyendo con el aumento del tamaño del nanocristal.
- Los potenciales interpartículas más suaves para los nanocristales más grandes favorecieron la formación de superredes gemelas múltiples.
Conclusiones:
- El tamaño del nanocristal es un determinante crítico de la morfología de la superretícula y el comportamiento de hermanamiento.
- La energía de hermanamiento dependiente del tamaño y los potenciales interpartículas gobiernan el resultado de la autoensamblaje.
- Este estudio introduce una nueva clase de materiales gemelados múltiples con potencial para interacciones interpartículas a medida.
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