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Entender el ensamblaje de nanocubo con la reconstrucción de un diagrama de fase de superretícula consistente
Xin Huang1, Jinlong Zhu2, Binghui Ge3
1Cornell High Energy Synchrotron Source , Cornell University , Ithaca , New York 14853 , United States.
Journal of the American Chemical Society
|January 29, 2019
Resumen
Este estudio revela cómo los ensamblajes de nanocubo de óxido de hierro forman diversas superredes. Comprender las vías de nucleación y crecimiento es clave para diseñar materiales avanzados basados en nanocubo.
Área de la Ciencia:
- Ciencias de los materiales
- Nanotecnología
- La cristalografía
Sus antecedentes:
- Los ensamblajes de nanocubo (NC) exhiben comportamientos complejos de superretícula.
- La comprensión sistemática de la nucleación, el crecimiento y la transformación de NC es crucial para la construcción del diagrama de fase.
Objetivo del estudio:
- Investigar el ensamblaje de nanocubos de óxido de hierro (NCs Fe3O4) en varias superredes 3D y 2D.
- Para aclarar los mecanismos de nucleación y crecimiento que rigen la formación de superredes.
- Establecer un diagrama de fase de superred y comprender las vías de transformación.
Principales métodos:
- Experimentos controlados con Fe3O4 NC bajo entornos específicos.
- Diseminación de rayos X in situ y estática de ángulo pequeño (SAXS) para el análisis estructural.
- Imágenes por microscopio electrónico para visualizar estructuras de superred.
- Modelado computacional para comprender la dinámica del ensamblaje.
Principales resultados:
- Los Fe3O4 NC se ensamblan en polímeros cúbicos simples (sc), cúbicos centrados en el cuerpo (bcc), cúbicos centrados en la cara (fcc), romboédricos (rh) y en redes cuadradas y hexagonales 2D.
- Fcc y bcc polimorfos nucleados principalmente en los planos de embalaje altos (fcc{111}, bcc{110}).
- El estrés de confinamiento durante el crecimiento indujo transformaciones de fcc/bcc a polimorfos rh.
- Se observó una simple distorsión romboédrica, impulsada por la tensión de compresión, en lugar de las vías tradicionales.
Conclusiones:
- El estudio establece un diagrama de fase consistente para las superredes basadas en NC.
- Las vías de ensamblaje y los mecanismos de transformación proporcionan información para el diseño de materiales funcionales.
- La fabricación controlada de superredes deseadas es posible para propiedades colectivas a medida.
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