Frustración del embalaje electrónico en estructuras intermetálicas complejas: el papel de la presión química en
1Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA. danny@chem.wisc.edu
Journal of the American Chemical Society
|May 31, 2011
Resumen
La frustración de embalaje electrónico (EPF) en compuestos intermetálicos surge de la competencia entre el tamaño atómico y los efectos electrónicos. Este estudio presenta un modelo y un método para analizar el EPF, revelando su papel en la conducción de la formación de defectos en Ca2Ag7.
Área de la Ciencia:
- Química del estado sólido.
- Ciencia de los materiales ciencia de los materiales.
- Química computacional es la química computacional.
Sus antecedentes:
- Las racionalizaciones químicas tradicionales a menudo separan los efectos electrónicos y estéricos.
- Los compuestos intermetálicos demuestran cada vez más una interacción entre el tamaño atómico y las interacciones orbitales.
- El empaque atómico denso en los intermetálicos puede conducir a una optimización conflictiva de las longitudes de enlace y las interacciones electrónicas.
Objetivo del estudio:
- Proponer un modelo para la frustración de embalaje electrónico (EPF) en compuestos intermetálicos.
- Desarrollar un método teórico para cuantificar las presiones químicas (PC) derivadas de EPF.
- Investigar el papel del EPF en la formación de estructuras de defectos en la intermetálica.
Principales métodos:
- Desarrollo de un modelo teórico para la frustración del embalaje electrónico (EPF).
- Cálculos de Hückel calibrados por DFT para sondear los efectos de la presión química (CP).
- Aplicación del método para analizar la estructura Ca(2)Ag(7) y las fases hipotéticas relacionadas.
Principales resultados:
- La formación de la estructura Ca(2)Ag(7) es impulsada por la frustración de embalaje electrónico (EPF).
- Los planos de defectos en Ca2Ag7 resuelven efectivamente las severas presiones químicas (CPs) alrededor de los átomos de Ca.
- Se identifica un análogo CP de la paradoja presión-distancia, explicando las características estructurales observadas.
Conclusiones:
- La frustración de embalaje electrónico (EPF) es un factor clave en la química estructural de los compuestos intermetálicos.
- La inserción de planos de defecto es un mecanismo para aliviar las presiones químicas significativas (CPs).
- La fuerza motriz para la formación del plano de defecto es sintonizable a través del control del recuento de electrones.
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