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Prefusión en los defectos dentro de los cristales coloidales a granel.

A M Alsayed¹, M F Islam, J Zhang

¹Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104-6396, USA.

Science (New York, N.Y.)

|July 5, 2005

Resumen

Este resumen es generado por máquina.

Los investigadores observaron la prefusión, un precursor de la fusión, dentro de los cristales coloidales en defectos como los límites de los granos y las dislocaciones. Este hallazgo amplía nuestra comprensión del comportamiento de los cristales y el papel de la energía libre interfacial.

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Área de la Ciencia:

Ciencia de los materiales Ciencia de los materiales.
Física de la materia condensada Física de la materia condensada
Ciencia de la coloide Ciencia de las coloides.

Sus antecedentes:

La premelatación es la pérdida localizada del orden cristalino por debajo del punto de fusión masivo.
Anteriormente, la prefusión solo se observaba en las superficies de los cristales, no dentro de la masa.
La comprensión de la prefusión es clave para comprender el comportamiento de los materiales cerca de las transiciones de fase.

Objetivo del estudio:

Para investigar el fenómeno de la prefusión dentro de la masa de cristales coloidales.
Identificar las ubicaciones y condiciones en las que se produce internamente la prefusión.
Para explorar la relación entre los defectos y la pre-fusión en los sistemas coloidales.

Principales métodos:

Se utilizó microscopía de video en tiempo real para observar cristales coloidales.
Empleado el rastreo de partículas para analizar el orden y el desorden cristalino.
Estructuras coloidales tridimensionales de equilibrio estrechamente empaquetadas sintetizadas a partir de esferas de microgel.

Principales resultados:

Se ha observado la prefusión en los límites de los granos y las dislocaciones dentro de los cristales coloidales a granel.
Desorden aumentado cuantificado cerca de los defectos, dependiendo del tipo de defecto y la distancia.
Se demostró que la fracción de volumen de las partículas influye en la extensión de la prefusión.

Conclusiones:

La prefusión ocurre dentro de los cristales coloidales en los defectos internos, no sólo en las superficies.
La energía libre de la interfaz se identifica como un parámetro crítico que rige la prefusión.
Los hallazgos tienen implicaciones tanto para los fenómenos de prefusión de cristales a escala coloidal como atómica.