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Una disminución inesperada en la entropía vibratoria de los óxidos de rutilo multicomponentes
Yaowen Wang1, Xinbo Li1, Jipeng Luo2
1State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
Journal of the American Chemical Society
|May 14, 2024
Resumen
La entropía vibratoria, a menudo pasada por alto en los óxidos de alta entropía (HEOs), afecta significativamente su estabilidad térmica. Este estudio confirma su papel crucial en la reducción de las temperaturas de cristalización de los OHE de rutilo multicomponentes.
Área de la Ciencia:
- Ciencias de los materiales
- La termodinámica
- Química del estado sólido
Sus antecedentes:
- Los óxidos de alta entropía (HEOs) poseen propiedades únicas debido a sus composiciones complejas.
- La entropía de configuración es ampliamente aceptada como el principal factor de la estabilidad térmica HEO.
- La contribución de la entropía vibratoria a la termodinámica HEO sigue siendo en gran medida inexplorada.
Objetivo del estudio:
- Investigar sistemáticamente el papel de la entropía vibratoria en los óxidos de rutilo multicomponentes.
- Determinar cómo el desorden de los componentes afecta la entropía vibratoria en estos materiales.
- Para aclarar la influencia del exceso de entropía vibratoria en la temperatura de cristalización de los OHE.
Principales métodos:
- Se realizaron mediciones precisas de la capacidad térmica de varios óxidos de rutilo multicomponentes.
- El análisis incluyó el examen del desorden de configuración, el desajuste de tamaño, las transiciones de fase y las distorsiones poliédricas.
- Se calculó la entropía vibratoria y se correlacionó con las características del material.
Principales resultados:
- La entropía vibratoria disminuye con el aumento del desorden de los componentes, desviándose de las predicciones de equilibrio.
- Todos los óxidos de rutilo multicomponentes estudiados presentan un exceso de entropía vibratoria positiva a 298,15 K.
- El exceso de entropía vibratoria fue identificado como un factor clave en la reducción de la temperatura de cristalización.
Conclusiones:
- Esta investigación proporciona la primera evidencia experimental del papel significativo de las vibraciones de celosía en el paisaje termodinámico de los OES de rutilo.
- La entropía vibratoria es un factor crítico que influye en el comportamiento térmico y el procesamiento de HEOs.
- La entropía vibratoria se puede utilizar como un nuevo descriptor para diseñar nuevos materiales de óxido multicomponentes.
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