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Cambios de coordinación y especiación del silicio en un líquido de silicato a altas presiones
Science (New York, N.Y.)
|September 1, 1989
Resumen
La alta presión transforma el silicio (Si) en líquidos de silicato, cambiando su geometría local. Este estudio detectó cambios inducidos por la presión en la coordinación de Si utilizando la RMN de (29) Si, revelando un cambio hacia el Si octaédrico en fases amorfas.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Ciencia de los materiales Ciencia de los materiales.
- Química del estado sólido.
Sus antecedentes:
- La coordinación y la geometría local de los cationes de silicio (Si) en líquidos de silicato son fundamentales para las propiedades del magma.
- Comprender estos cambios estructurales bajo presión es esencial para la geoquímica y la ciencia de los materiales.
Objetivo del estudio:
- Para investigar los cambios inducidos por la presión en la coordinación de Si en vidrios de silicato.
- Para caracterizar la estructura atómica local de Si en fases amorfas bajo alta presión.
Principales métodos:
- Se utilizó la espectrometría de resonancia magnética nuclear (MAS NMR) giratoria de ángulo mágico (29) Si.
- Se analizaron muestras de vidrio disilicado de sodio (Na2Si2O5) apagadas a alta presión (8 GPa) y temperatura (1500 °C).
Principales resultados:
- Se detectó la presencia de aproximadamente el 1,5% de Si octaédrico en vidrios apagados a 8 GPa y 1500 °C.
- Se ha confirmado que el Si octaédrico forma parte de una fase amorfa homogénea.
- Desproporción observada de la especiación Si tetraédrica dominante hacia una distribución más aleatoria de oxígenos puentes y no puentes con presión creciente.
Conclusiones:
- La alta presión induce una transición en la coordinación de Si en vidrios de silicato.
- Los cambios estructurales observados influyen en la distribución de las especies de oxígeno alrededor de los silicatos.
- Estos hallazgos proporcionan información sobre el comportamiento de los líquidos de silicato en condiciones extremas.
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