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Characterization of Nanocrystal Size Distribution using Raman Spectroscopy with a Multi-particle Phonon Confinement Model
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Espectroscopia de RMN multinuclear en estado sólido de nanopartículas de fluoruro de lantano dopadas con
Andy Y H Lo1, Vasanthakumaran Sudarsan, Sri Sivakumar
1Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4.
Journal of the American Chemical Society
|March 28, 2007
Resumen
Este estudio utilizó RMN y XRD de estado sólido para caracterizar las nanopartículas LaF3 dopadas con lantánidos. Los resultados muestran que se conserva la estructura del núcleo, con modificaciones superficiales y distribución uniforme del dopante.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Nanotecnología La nanotecnología es la nanotecnología.
- Química del estado sólido.
Sus antecedentes:
- Las nanopartículas de fluoruro de lantano (LaF3) son cruciales en varias aplicaciones.
- Comprender la integridad estructural y la química superficial de las NP dopadas es esencial para optimizar sus propiedades.
- Es clave caracterizar el impacto del dopaje de lantánidos en la estructura de LaF3 NP y las interacciones de los ligandos.
Objetivo del estudio:
- Caracterizar exhaustivamente las nanopartículas LaF3 (NP) puras y dopadas con lantánidos y sus correspondientes materiales a granel.
- Para investigar la retención estructural del núcleo LaF3 tras el dopaje y la formación de NP.
- Para dilucidar la naturaleza de las interacciones de ligando de capping en la superficie NP.
Principales métodos:
- Espectroscopia de resonancia magnética nuclear (RMN) de estado sólido multinuclear (139La, 19F, 45Sc, 1H, 31P).
- Difracción de rayos X en polvo (XRD).
- Las técnicas de RMN de giro de ángulo mágico (MAS) y las técnicas de RMN de polarización cruzada (CP) / MAS.
Principales resultados:
- La RMN y la RDX de estado sólido confirmaron que la estructura de LaF3 se mantiene a nivel molecular en las NP.
- La ampliación inhomogénea en los espectros de RMN indicó un gradiente en los entornos La y F desde el núcleo de NP hasta la superficie.
- El dopaje de lantánidos (5-10 mol%) no alteró significativamente la estructura del núcleo NP, con los dopantes distribuidos uniformemente.
- El análisis de ligandos reveló ditiofosfato, tiofosfato y especies de fosfato en la superficie de NP, confirmando la coordinación de ligandos.
Conclusiones:
- Las nanopartículas LaF3 conservan su estructura central, pero exhiben modificaciones superficiales que afectan a los entornos locales.
- Los dopantes lantánidos se integran en los sitios de la red LaF3, distribuyéndose uniformemente dentro del núcleo NP.
- Los ligandos de di-n-octadectyldithiophosphate se coordinan con la superficie NP, con evidencia de productos de degradación del ligando.
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