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Concha de pasivación dependiente del tamaño y propiedades magnéticas en el núcleo/concha
Alberto López-Ortega1, Dina Tobia, Elin Winkler
1Centre d'Investigació en Nanociència i Nanotecnologia (ICN-CSIC), Campus Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain.
Journal of the American Chemical Society
|June 24, 2010
Resumen
La fase de las capas de pasivación en las nanopartículas de núcleo de óxido de manganeso (MnO) depende del tamaño, lo que influye en las propiedades magnéticas. Las nanopartículas más pequeñas muestran una mayor anisotropía magnética y temperaturas Néel.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Nanotecnología La nanotecnología es la nanotecnología.
- Física del estado sólido Física del estado sólido
Sus antecedentes:
- Las nanopartículas de núcleo / cáscara ofrecen propiedades sintonizables mediante la combinación de diferentes materiales.
- Los óxidos de manganeso (MnO) exhiben diversos comportamientos magnéticos dependiendo de la fase y la estructura.
Objetivo del estudio:
- Para investigar las propiedades magnéticas de las nanopartículas de núcleo / cáscara bimagnéticas.
- Comprender la influencia del tamaño de las nanopartículas en la fase de la cáscara y las características magnéticas.
Principales métodos:
- Síntesis de nanopartículas de núcleo / cáscara con núcleo de MnO y cáscara ferrimagnética.
- Caracterización estructural para determinar la fase del caparazón (gamma-Mn{2}O{3} o Mn{3}O{4}.
- Caracterización magnética para evaluar la temperatura de Néel, la anisotropía magnética y el comportamiento del dominio.
Principales resultados:
- La composición de la fase del caparazón varía con el tamaño de las nanopartículas: gamma-Mn(2) O(3) domina en las partículas más pequeñas, Mn(3) O(4) aumenta en las más grandes.
- Mejora significativa de la temperatura de Néel (T(N)) y la anisotropía magnética en el núcleo de MnO con la disminución del tamaño del núcleo.
- Se observó un momento magnético persistente en MnO a altas temperaturas y una inusual dependencia de temperatura en el dominio magnético.
Conclusiones:
- El tamaño de las nanopartículas es un factor crítico que controla la fase y las propiedades magnéticas de los sistemas de núcleo / cáscara de MnO.
- Los fenómenos magnéticos dependientes del tamaño, incluida la T (N) mejorada y la anisotropía, son importantes para la comprensión fundamental y las aplicaciones potenciales.
- El estudio destaca la compleja interacción entre el tamaño, la fase y el magnetismo en los nanomateriales.
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