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Un mecanismo de conducción eléctrica a alta temperatura en la fase inferior del manto (Mg,Fe) 1-xOO
1Department of Geological Sciences, University College London, London WC1E 6BT, UK.
Science (New York, N.Y.)
|March 21, 1997
Resumen
La conductividad eléctrica en el manto inferior de magnesiowustite cambia con la temperatura. Un cambio de polarón pequeño a la conducción de polarón grande a altas temperaturas impacta los modelos del interior profundo de la Tierra.
Área de la Ciencia:
- Geofísica y física de los minerales.
- Estudios experimentales de alta presión y alta temperatura.
Sus antecedentes:
- El magnesiowustite es una fase clave en el manto inferior de la Tierra.
- Estudios previos a presión atmosférica sugirieron que el salto de Fe2+-Fe3+ (pequeño polarón) rige la conductividad.
Objetivo del estudio:
- Para investigar la conductividad eléctrica del magnesiowustite bajo condiciones del manto inferior (alta presión y temperatura).
- Para determinar el mecanismo de transporte de carga dominante a las temperaturas relevantes del manto.
- Para evaluar la influencia del contenido variable de Fe3+ en la conductividad.
Principales métodos:
- Mediciones experimentales de la conductividad eléctrica en magnesiowustite.
- Variación de la presión, la temperatura y el contenido de Fe3+.
- Análisis de los mecanismos de transporte de carga basado en datos experimentales.
Principales resultados:
- Las mediciones de conductividad eléctrica revelan un mecanismo de transporte de carga dependiente de la temperatura.
- A temperaturas más bajas, los resultados se alinean con una pequeña conducción polaron.
- A temperaturas más altas (relevantes para el manto), se indica un gran mecanismo de polarón.
Conclusiones:
- El mecanismo de transporte de carga en el magnesiowustite transiciones de polaron pequeño a grande con el aumento de la temperatura.
- Esta transición tiene implicaciones significativas para interpretar los datos geofísicos y modelar las propiedades eléctricas del manto inferior.
- Una extrapolación precisa a las condiciones del manto requiere considerar este desplazamiento del mecanismo y sus dependencias de composición.
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