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Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction
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Fases modificadas de diamante formadas bajo compresión de choque y calentamiento rápido
Science (New York, N.Y.)
|August 16, 1991
Resumen
Los investigadores crearon dos nuevas formas de carbono a partir del grafito golpeado. Uno, el n-diamante, es una estructura cúbica metastable similar al diamante, mientras que el otro es el resultado de la reconstrucción.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física de las altas presiones Física de las altas presiones
- Todos los carbonos son alotrópicos.
Sus antecedentes:
- El grafito es un conocido alotrópico de carbono con una estructura en capas.
- Las condiciones de alta presión y alta temperatura pueden transformar el grafito en nuevas estructuras de carbono.
- Comprender estas transformaciones es clave para desarrollar nuevos materiales con propiedades únicas.
Objetivo del estudio:
- Para investigar la formación de nuevas fases de carbono a partir del grafito bajo extrema compresión de choque.
- Caracterizar las estructuras cristalinas y las propiedades de estas nuevas formas de carbono.
- Para dilucidar los mecanismos de transformación del grafito a las nuevas fases.
Principales métodos:
- Las láminas de grafito fueron sometidas a una compresión de choque que alcanzó los 65 gigapascales y 3700 K.
- Se empleó una técnica de enfriamiento rápido para calmar las muestras comprimidas.
- Se realizó un análisis estructural en los materiales de carbono resultantes.
Principales resultados:
- Se sintetizaron con éxito dos formas distintas de carbono modificado.
- La porción rápidamente enfriada dio como resultado 'n-diamante', exhibiendo una estructura cristalina similar al diamante cúbico.
- Una porción de enfriamiento más lento produjo una segunda forma comparable al i-carbono sintetizado por haz de iones, formado a través de la reconstrucción.
Conclusiones:
- El diamante N se propone como una forma metastable, potencialmente relacionada con el diamante hexagonal, formado a través de una transición martensítica del grafito.
- La vía de formación o región para el n-diamante puede diferir de la del diamante hexagonal.
- La segunda forma de carbono surge de un proceso de reconstrucción atómica.
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