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Termoeléctricas GeTe de alto rendimiento tanto en fases romboédricas como cúbicas
Juan Li1, Xinyue Zhang1, Xiao Wang1
1Interdisciplinary Materials Research Center, School of Materials Science and Engineering , Tongji University , Shanghai 201804 , China.
Journal of the American Chemical Society
|October 27, 2018
Resumen
El dopaje de antimonio en el tellururo de germanio (GeTe) optimiza el rendimiento termoeléctrico al mejorar la degeneración de la banda y reducir la conductividad térmica. Esta investigación alcanza una alta cifra de mérito termoeléctrico (zT) superior a 2 tanto en las fases GeTe cúbicas como en las romboédricas.
Área de la Ciencia:
- Ciencias de los materiales
- Física del estado sólido
- Materiales termoeléctricos
Sus antecedentes:
- El tellururo de germanio (GeTe) muestra transiciones de fase entre estructuras cúbicas y romboédricas.
- El GeTe cúbico y los semiconductores IV-VI relacionados poseen una estructura de dos bandas de valencia (bandas L y Σ) beneficiosa para el rendimiento termoeléctrico debido a la alta degeneración de banda.
- El GeTe romboédrico muestra un ordenamiento y división alterados de la banda, ofreciendo nuevas vías para manipular la degeneración de la banda.
Objetivo del estudio:
- Para optimizar la concentración del portador y manipular la distorsión de la celosía en GeTe utilizando dopaje de antimonio (Sb).
- Para maximizar la degeneración de banda y mejorar el rendimiento electrónico de los termoeléctricos basados en GeTe.
- Para reducir la conductividad térmica de la red a través de la dispersión de fonones inducida por Sb-doping.
Principales métodos:
- Dopaje de antimonio (Sb) con telururo de germanio (GeTe).
- Investigación de la concentración del portador y de la distorsión de la red romboédrica.
- Análisis de la manipulación de la estructura de la banda y los mecanismos de dispersión de fonones.
Principales resultados:
- El Sb-doping optimizó con éxito la concentración del portador y la distorsión de la red romboédrica controlada.
- El Sb-doping aumentó la degeneración de la banda y promovió la solubilidad de PbTe, lo que condujo a un aumento de la dispersión de fonones por defectos de sustitución de Ge/Pb.
- Se logró una cifra de mérito termoeléctrico superior (zT) de más de 2 tanto en fases romboédricas como cúbicas de GeTe a temperaturas inferiores a 800 K.
Conclusiones:
- Las aleaciones de GeTe dopadas con Sb demuestran excelentes propiedades termoeléctricas, posicionándolas como candidatos líderes para aplicaciones por debajo de 800 K.
- El estudio destaca el papel crítico de la manipulación de la simetría de la estructura cristalina en el avance de los materiales termoeléctricos.
- Este trabajo proporciona una vía para diseñar termoeléctricos de alto rendimiento a través de dopaje controlado y modificaciones estructurales.
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