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Observaciones in situ de una fase de alta presión del hielo H2O
1I. Chou, 955 National Center, U.S. Geological Survey, Reston, VA 20192, USA. J. G. Blank, A. F. Goncharov, H. Mao, R. J. Hemley, Geophysical Laboratory and Center for High Pressure Research, Carnegie Institution of Washington, 5251 Broad.
Science (New York, N.Y.)
|August 7, 1998
Resumen
Los científicos descubrieron una nueva fase sólida del agua (H2O) con estructuras cristalinas únicas y comportamientos de fusión. Este hallazgo amplía nuestra comprensión del agua.
Área de la Ciencia:
- Química del estado sólido.
- Ciencia de los materiales ciencia de los materiales.
- La geofísica es la geofísica.
Sus antecedentes:
- El agua (H2O) existe en numerosas fases sólidas (hielos) bajo diferentes condiciones de presión y temperatura.
- Comprender estas fases es crucial para la ciencia planetaria y la física de altas presiones.
- Investigaciones anteriores han identificado muchos polimorfos de hielo, pero el diagrama de fase completo sigue siendo incompleto.
Objetivo del estudio:
- Para identificar y caracterizar fases sólidas de agua previamente desconocidas.
- Investigar las relaciones de fusión presión-temperatura y las propiedades estructurales de estas fases.
Principales métodos:
- Observación directa del crecimiento y la fusión de los cristales de hielo utilizando una célula hidrotermal de yunque de diamante.
- Análisis de las densidades masivas de H2O que van desde 1203 hasta 1257 kg/m3.
- Las mediciones se llevaron a cabo a temperaturas entre -10°C y 50°C.
- Caracterización mediante espectroscopia Raman vibratoria.
Principales resultados:
- Identificación de una nueva fase sólida previamente desconocida de H2O.
- Se observaron patrones de crecimiento distintos y relaciones de fusión presión-temperatura para la nueva fase.
- La nueva fase de hielo exhibe una estructura anisotrópica desordenada, que muestra similitudes con el hielo VI.
- Se observó que cuatro formas de hielo (hielo V, VI, IV y la nueva fase) se derritieron en condiciones experimentales.
Conclusiones:
- Se ha confirmado experimentalmente una nueva fase sólida del agua.
- La nueva fase posee propiedades estructurales y termodinámicas únicas.
- Este descubrimiento contribuye a una comprensión más completa del diagrama de fase H2O.
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