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Difusión de iones de cesio en la fusión granítica saturada de H2O
Science (New York, N.Y.)
|September 21, 1979
Resumen
El agua disuelta acelera significativamente la difusión del cesio-134 en las fusiones graníticas. Este hallazgo sugiere tiempos de equilibrio de procesos químicos más rápidos en fundidos de silicato que contienen agua.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- La comprensión de la difusión iónica en fundidos geológicos es crucial para el modelado geoquímico.
- Estudios previos indican que el vidrio granítico seco exhibe tasas de difusión lentas.
Objetivo del estudio:
- Para investigar el efecto del agua disuelta en la auto-difusión del cesio-134 en la fusión granítica.
- Para cuantificar el cambio en los coeficientes de difusión y la energía de activación.
Principales métodos:
- Se llevaron a cabo experimentos de difusión de trazador radiactivo (cesio-134).
- Los experimentos se llevaron a cabo en la fusión granítica con 6.1-6.3 wt% disuelto H2O.
- La difusión se midió a 700-800°C y 2 kbar.
Principales resultados:
- Los coeficientes de difusión del cesio-134 fueron de 3 a 4 órdenes de magnitud más altos en presencia de agua.
- La energía de activación para la difusión fue de aproximadamente 20 kcal/mol, significativamente menor que en vidrio seco.
- La difusividad del cesio seguía la ecuación de Arrhenius: D = 7.19 x 10(-5) exp (-19.52 x 10(3) /RT).
Conclusiones:
- El agua disuelta mejora dramáticamente la movilidad iónica en fundidos graníticos.
- Esta mayor movilidad implica tiempos de equilibrio químico significativamente reducidos para los procesos geológicos en fundidos hidrosos.
- Los hallazgos tienen implicaciones para la comprensión del comportamiento del derretimiento en diversos entornos geológicos.
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