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Distribución en el espacio real del ordenamiento local de WO4 en la expansión térmica negativa ZrW2O8
Yukio Sato1, Yasuhisa Yamamura, Kazuya Saito
1Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo, Tokyo 113-8656, Japan. y_sato@sigma.t.u-tokyo.ac.jp
Journal of the American Chemical Society
|August 18, 2012
Resumen
El tungstato de zirconio exhibe una excepcional expansión térmica negativa (NTE). La nueva microscopía electrónica revela que el desorden de WO en nanoescala es clave para este fenómeno, ofreciendo información sobre sus propiedades únicas.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química del estado sólido.
- La cristalografía es una técnica de cristalografía.
Sus antecedentes:
- Los sólidos generalmente se expanden al calentarse, pero existen excepciones.
- El tungstato de zirconio (ZrW ((2) O ((8)) es un material notable que exhibe una expansión térmica negativa significativa (NTE) en un amplio rango de temperatura.
- Estudios anteriores destacaron el papel de los poliedros de metal-oxígeno en los mecanismos de NTE, pero carecían de detalles microscópicos.
Objetivo del estudio:
- Para investigar el ordenamiento local de los tetraedros WO(4) en ZrW(2)O(8) utilizando microscopía electrónica avanzada.
- Para entender los orígenes microscópicos de la expansión térmica negativa en ZrW(2)O(8).
- Desarrollar un modelo de microestructura para ZrW(2)O(8) basado en observaciones en el espacio real.
Principales métodos:
- Observaciones de microscopía electrónica de alta resolución.
- Imágenes en el espacio real de la distribución local de los tetraedros WO(4).
- Análisis de los fenómenos de ordenamiento y desordenamiento a nanoescala.
Principales resultados:
- El estudio proporciona la primera observación directa del ordenamiento local de los tetraedros WO(4) en ZrW(2)O(8).
- Los hallazgos clave incluyen el ordenamiento parcialmente invertido de WO(4) y el desordenamiento a nanoescala de WO(4).
- Se observó que el dopaje con escandio aumentaba el grado de trastorno de la WO.
Conclusiones:
- El desorden observado a nanoescala WO(4) es crucial para comprender el comportamiento negativo de expansión térmica de ZrW(2)O(8).
- Se ha propuesto un nuevo modelo de microestructura para ZrW(2)O(8), que ofrece una perspectiva refinada de su estructura local.
- Estos hallazgos son vitales para comprender el papel de la estructura local en las transiciones de fase y para diseñar materiales con propiedades de expansión térmica a medida.
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