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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
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Efectos de muchos cuerpos en superretas nanocristalinas: la desviación del empaquetado esférico explica la
Michael A Boles1, Dmitri V Talapin1
1University of Chicago and James Franck Institute, Chicago, Illinois 60637, United States.
Journal of the American Chemical Society
|March 17, 2015
Resumen
Las superredes de nanocristales exhiben un embalaje denso independientemente de la suavidad del ligando. Las capas de ligandos se deforman, lo que permite a las partículas adaptar su tamaño para un llenado eficiente del espacio en sistemas binarios.
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:
- Las superredes de nanocristales (NC) se ensamblan a partir de NCs cubiertas con ligandos.
- El caparazón del ligando influye en el tamaño efectivo y el comportamiento de empaque de los NC.
- Comprender el embalaje NC es crucial para el diseño de materiales avanzados.
Objetivo del estudio:
- Para analizar el papel de los ligandos de hidrocarburos en el autoensamblaje de la superred nanocristalina.
- Para investigar la influencia de la suavidad del ligando en la densidad y estructura de embalaje NC.
- Para entender la deformación de partículas en las superredes de nanocristales binarios (BNSL).
Principales métodos:
- Mediciones de seguimiento de partículas a partir de imágenes de microscopía electrónica de transmisión (TEM). imágenes.
- Análisis de la suavidad del nanocristal (NC) utilizando la relación entre la longitud del ligando y el radio del núcleo (L/R).
- Fabricación y caracterización de superredes de nanocristales binarios (BNSL) con suavidad NC variable.
Principales resultados:
- Las NCs estrechamente empaquetadas logran una densidad de aproximadamente 74%, similar a las esferas duras, independientemente de la suavidad del ligando.
- La capa de tapa de ligando exhibe deformabilidad, lo que lleva a un tamaño NC efectivo variable.
- La deformación NC permite BNSLs densos, incluso en configuraciones que serían de baja densidad si las partículas permanecieran esféricas.
Conclusiones:
- La deformabilidad de los nanocristales es un factor clave para lograr un embalaje denso de superretícula.
- El empaque de BNSLs puede ser racionalizado por la deformación de partículas en lugar de complejas interacciones energéticas.
- Los hallazgos contribuyen a comprender los efectos entrópicos en la cristalización de objetos deformables.
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