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Triangulación del nivel de dopaje Mn(II) Inserción en una perovskita doble Cs2NaBiCl6 utilizando espectroscopia de
Abhoy Karmakar1, Guy M Bernard1, Arkadii Pominov1
1Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
Journal of the American Chemical Society
|February 14, 2023
Resumen
Este estudio utiliza la resonancia magnética para investigar las perovskitas dobles sin plomo dopadas con manganeso. El dopaje de manganeso se produce en los sitios de bismuto, influyendo en el material
Área de la Ciencia:
- Ciencias de los materiales
- Química del estado sólido
- Espectroscopia
Sus antecedentes:
- Las perovskitas dobles de haluro metálico sin plomo son prometedoras para la optoelectrónica.
- El dopaje con metales de transición sintoniza las brechas ópticas.
- El sitio de incorporación de Mn (II) en Cs2NaBiCl6 es poco conocido a bajos niveles de dopaje.
Objetivo del estudio:
- Para determinar la estructura a nivel atómico de la incorporación de Mn (II) en Cs 2 NaBiCl 6.
- Comprender las relaciones estructura-propiedad para aplicaciones optoelectrónicas avanzadas.
- Para elucidar el sitio de la inserción de Mn (II) utilizando técnicas de resonancia magnética.
Principales métodos:
- Un enfoque multi-técnico que combina la resonancia magnética nuclear de estado sólido (NMR), la polarización nuclear dinámica (DNP) y las espectroscopias de resonancia paramagnética de electrones (EPR).
- La RMN multinuclear (Na23, Cl35, Cs209, Bi) para sondear los entornos locales.
- Espectroscopia de correlación de subnivel EPR y HYSCORE para identificar el estado de oxidación, la simetría y las interacciones de Mn.
Principales resultados:
- Se detectaron bajos niveles de incorporación de Mn{II}, con espines afectados que muestran una mejora de la relajación paramagnética (PRE).
- EPR confirmó el Mn (II) en simetría octaédrica, sin correlaciones Bi en HYSCORE que sugieran la sustitución en los sitios Bi.
- La RMN y la EPR indicaron una estructura cúbica a temperatura ambiente, con desviaciones por debajo de 30 K. La RMN DNP apoyó una distribución homogénea de Mn{II}.
Conclusiones:
- Mn (II) sustituye al Bi en la estructura doble de perovskita de Cs2 y NaBiCl6.
- El material mantiene la simetría cúbica a temperatura ambiente, pero muestra desviaciones a bajas temperaturas.
- Las técnicas de resonancia magnética aclararon con éxito el sitio de incorporación y distribución de Mn{II}, avanzando la comprensión para aplicaciones optoelectrónicas.
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