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Las transiciones magnéticas agudas protegidas por alta entropía en ferritas de espinillo altamente desordenadas
Lujin Min1,2, John P Barber3,4, Yu Wang1,5
1Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Journal of the American Chemical Society
|August 20, 2024
Resumen
Los óxidos de alta entropía con alto desorden muestran transiciones magnéticas agudas. La síntesis de cristales individuales revela una distribución elemental aleatoria que mejora la homogeneidad y preserva el ordenamiento magnético, abriendo nuevas vías de investigación.
Área de la Ciencia:
- Ciencias de los materiales
- Física de la materia condensada
- Química del estado sólido
Sus antecedentes:
- Investigar los efectos del trastorno en el ordenamiento magnético de los materiales es crucial.
- Los óxidos de alta entropía (HEOs) presentan densidades de desorden extremo, lo que complica el comportamiento magnético.
- La falta de cristales únicos de alta calidad ha limitado la investigación profunda sobre los efectos de los trastornos de la composición de HEO.
Objetivo del estudio:
- Para sintetizar ferritas de espinela monocristalinas de alta calidad y alta entropía.
- Investigar el impacto de los trastornos de la composición en las transiciones magnéticas en las HEO.
- Comprender la relación entre la distribución elemental y el ordenamiento magnético en las OSE.
Principales métodos:
- Síntesis de las ferritas de espinela monocristalinas de alta entropía (Mg0.2Mn0.2Fe0.2Co0.2Ni0.2) Fe3-xO4.
- Mediciones de magnetización a alta temperatura.
- Experimentos de difracción de neutrones.
- Mediciones de la estructura fina de absorción de rayos X extendida (EXAFS).
Principales resultados:
- Las transiciones ferrimagnéticas observadas a 748 K (x = 1), 694 K (x = 1.5) y 674 K (x = 1.8).
- Las transiciones magnéticas mostraron una ampliación mínima para x = 1 y x = 1.5, a diferencia de Fe3O4.
- EXAFS reveló una distribución elemental aleatoria, reduciendo las agrupaciones locales y las órdenes de corto alcance.
- Mejora de la homogeneidad de la muestra y conservación de las transiciones magnéticas agudas a pesar de las variaciones en la longitud del enlace.
Conclusiones:
- Síntesis exitosa del primer cristal único HEO a granel con orden magnético de largo alcance.
- La distribución elemental aleatoria en los HEO mejora la homogeneidad y agudiza las transiciones magnéticas.
- Interacción demostrada entre la alta entropía de configuración y el ordenamiento magnético en las HEOs.
- Abrió nuevas vías para la investigación y las aplicaciones de óxidos magnéticos de alta entropía.
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