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La estructura cristalina inducida por la presión y las transiciones de estado de giro en la magnetita (Fe3O4)
Sheng Ju1, Tian-Yi Cai, Hai-Shuang Lu
1Department of Physics and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, PR China. jusheng@suda.edu.cn
Journal of the American Chemical Society
|July 25, 2012
Resumen
La alta presión altera significativamente las propiedades magnéticas y estructurales de la magnetita (Fe3O4). Se identifican nuevas fases de alta presión, lo que explica los resultados experimentales y sugiere la presencia de magnetita en el manto inferior de la Tierra.
Área de la Ciencia:
- Física de la materia condensada Física de la materia condensada
- Ciencia de los materiales Ciencia de los materiales.
- La geofísica es la geofísica.
Sus antecedentes:
- La alta presión es crucial para los fenómenos emergentes en los óxidos de metales de transición.
- El comportamiento de la magnetita (Fe3O4) bajo alta presión sigue sin estar claro, particularmente su estructura cristalina.
- La interacción de la red, la carga, el orbital y el giro en sistemas correlacionados es sensible a la presión.
Objetivo del estudio:
- Investigar las transiciones de fase inducidas por presión en Fe(3) O(4) utilizando cálculos basados en los primeros principios.
- Aclarar la polémica estructura cristalina de alta presión de la magnetita.
- Explique las propiedades estructurales y magnéticas observadas del Fe altamente comprimido (((3) O ((4)).
Principales métodos:
- Primeros principios cálculos de la teoría de la densidad-funcional.
- Análisis de las transiciones estructurales inducidas por la presión.
- Investigación del momento magnético y los cambios de ocupación orbital de Fe 3d.
Principales resultados:
- Se identificaron sucesivas transiciones estructurales: Fd3[combinación de línea general]m a Pbcm (a 29,7 GPa) y luego a Bbmm (a 65,1 GPa).
- Se observó una caída abrupta en el momento magnético neto al entrar en la fase de alta presión.
- Recuperación determinada del momento magnético finito más allá de 65.1 GPa debido a la redistribución orbital Fe 3d y los cambios en el campo cristalino.
Conclusiones:
- Fases estructurales de alta presión de Fe ((3) O ((4)) establecidas con precisión.
- Observaciones experimentales explicadas de las propiedades estructurales y magnéticas bajo compresión.
- Sugirió la existencia de magnetita altamente magnetizada en el manto inferior de la Tierra.
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