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Susceptibilidad magnética del carbono molecular: los nanotubos y la fullerita
Science (New York, N.Y.)
|July 1, 1994
Resumen
Los nanotubos de carbono exhiben una mayor susceptibilidad magnética que otras formas de carbono, lo que sugiere una estructura de banda similar al grafito. C(60) muestra un salto de susceptibilidad magnética relacionado con el ordenamiento molecular.
Área de la Ciencia:
- Física de la materia condensada Física de la materia condensada
- Ciencia de los materiales Ciencia de los materiales.
- Nanotecnología La nanotecnología es la nanotecnología.
Sus antecedentes:
- El carbono elemental existe en diversas formas, incluyendo el diamante, el grafito, los fullerenos (como el C60) y los nanotubos.
- Las propiedades magnéticas de los nanotubos de carbono y la fullerita C60) son menos conocidas en comparación con otros alótropos de carbono.
- La susceptibilidad magnética proporciona información sobre la estructura de las bandas electrónicas y las interacciones intermoleculares.
Objetivo del estudio:
- Para investigar y comparar la susceptibilidad magnética de los nanotubos de carbono y la fullerita C60.
- Para aclarar la relación entre la estructura molecular, las interacciones intermoleculares y las propiedades magnéticas en estas formas de carbono.
- Comprender la estructura de la banda electrónica de los nanotubos y la influencia de las transiciones ordenadas en las propiedades de la fullerita.
Principales métodos:
- Medición de la susceptibilidad magnética para los nanotubos de carbono.
- Mediciones de susceptibilidad magnética de alta resolución para la fullerita C60) cerca de su transición de ordenamiento de orientación.
- Análisis de datos de susceptibilidad para inferir la estructura de la banda y los efectos cooperativos.
Principales resultados:
- Los nanotubos de carbono demuestran una sensibilidad magnética por átomo de carbono significativamente mayor en comparación con otras formas elementales de carbono.
- La susceptibilidad magnética de los nanotubos sugiere una estructura de banda promedio análoga a la del grafito.
- Se observó un fuerte salto en la susceptibilidad magnética (2,5 cgs ppm / mol C60) en la fullerita C60) a 259 K, coincidiendo con la transición de ordenamiento de orientación molecular.
Conclusiones:
- Los nanotubos de carbono poseen propiedades electrónicas únicas que se reflejan en su mayor susceptibilidad magnética.
- El salto de susceptibilidad observado en la fullerita C ((60) proporciona evidencia directa de efectos de cooperación intermolecular que influyen en las propiedades electrónicas intramoleculares.
- Las fuerzas del enrejado y los cambios de forma molecular son probablemente responsables de la anomalía de susceptibilidad en la fullerita C60) durante el pedido.
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