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Ordenamientos de cargas de sitio A y sitio B en un nivel controlado de óxido de perovskita PbCoO3
Yuki Sakai1, Junye Yang2, Runze Yu3
1Kanagawa Academy of Science and Technology , KSP, 3-2-1 Sakado, Takatsu-ku, Kawasaki City, Kanagawa 213-0012, Japan.
Journal of the American Chemical Society
|February 28, 2017
Resumen
La perovskita sintetizada PbCoO3 exhibe un orden de carga único tanto en iones de plomo como en cobalto, formando una estructura cuadruple de perovskita Pb2 + Pb4 + 3Co2 + 2Co3 + 2O12. Esta distribución de carga compleja fue confirmada a través de varias técnicas avanzadas de caracterización de materiales.
Área de la Ciencia:
- Ciencias de los materiales
- Química del estado sólido
- Física de la materia condensada
Sus antecedentes:
- Los óxidos de perovskita (ABO3) son conocidos por sus diversas propiedades electrónicas y magnéticas.
- El orden de carga en perovskitas puede conducir a nuevas funcionalidades.
- Comprender los estados de valencia complejos es crucial para el diseño de materiales.
Objetivo del estudio:
- Investigar la distribución de la carga en la perovskita PbCoO3 sintetizada bajo alta presión.
- Para aclarar la formación de una estructura de perovskita cuádruple con orden de carga.
- Para explorar los mecanismos de estabilización de estos estados de valencia únicos.
Principales métodos:
- Síntesis bajo alta presión (12 GPa).
- Cálculos de la teoría funcional de la densidad (DFT).
- Análisis estructurales y espectroscópicos avanzados: difracción de electrones (ED), difracción de rayos X sincrotrón (SXRD), difracción de polvo de neutrones (NPD), espectroscopia de fotoemisión de rayos X duros (HAXPES), espectroscopia de absorción de rayos X blandos (XAS).
- Medidas de propiedades físicas: propiedades térmicas, magnéticas y eléctricas específicas.
Principales resultados:
- Descubrimiento de una distribución de carga inusual: Pb2+Pb4+3Co2+2Co3+2O12.
- Pruebas de ordenamiento de carga en los sitios A (Pb) y B (Co) de la estructura de perovskita.
- Confirmación de una estructura cuadruple de perovskita.
- Demostración de que el ajuste de las energías orbitales Pb 6s y metal de transición 3d estabiliza la valencia promedio de Pb3.5 + Co2.5 + O3.
Conclusiones:
- La perovskita PbCoO3 bajo alta presión exhibe un orden de carga intrincado que conduce a una nueva estructura de perovskita cuádruple.
- El orden de carga observado influye significativamente en las propiedades del material.
- El ajuste de las energías orbitales electrónicas ofrece una vía para controlar y estabilizar los estados de valencia complejos en las perovskitas.
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