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Ajuste de la transición de fase asistida por transferencia de carga y las funcionalidades de relajación magnética
Szymon Chorazy1,2, Jan J Stanek3, Wojciech Nogaś1
1Faculty of Chemistry, Jagiellonian University , Ingardena 3, 30-060 Kraków, Poland.
Journal of the American Chemical Society
|January 14, 2016
Resumen
Este estudio sintetiza nuevos grupos de hierro-cobalto-tungsteno con propiedades magnéticas ajustables. La relación entre los iones de hierro y cobalto controla la transferencia de carga, las transiciones de fase y la relajación magnética, lo que permite un control preciso de la funcionalidad del material.
Área de la Ciencia:
- Química inorgánica
- Ciencias de los materiales
- Magnetoquímica
Sus antecedentes:
- Los compuestos de coordinación con puente de cianuro ofrecen propiedades electrónicas y magnéticas sintonizables.
- Los sólidos moleculares basados en clústeres proporcionan una plataforma para el diseño de materiales con funcionalidades específicas.
- Controlar las relaciones de iones metálicos en grupos de metales mezclados es clave para afinar sus propiedades.
Objetivo del estudio:
- Para sintetizar una serie de isostruturales {Fe{9-x}Co{x}[W{CN}8]6{MeOH}24}·12 MeOH racimos con diferentes proporciones de hierro y cobalto.
- Investigar el impacto de la estequiometría controlada de Co/Fe en las funcionalidades magnéticas de estos grupos.
- Para aclarar la relación entre la transferencia de carga, las transiciones de fase y los fenómenos de relajación magnética.
Principales métodos:
- Combinación estequiométrica de Co2+, Fe2+ y [WV]CN8]3-) en el metanol.
- Caracterización estructural de grupos pentadecanucleares con una topología de cubo centrada en el cuerpo de seis tapas.
- Estudios espectroscópicos y magnéticos para analizar la transferencia de carga, el cruce de espín y la relajación magnética.
Principales resultados:
- Se sintetizó con éxito una serie de grupos isostruturales {Fe{9-x) Co{-x) {W{-CN}8{-MeOH}24}·12MeOH (x=0-9).
- Las fases ricas en hierro (0-5) exhiben transiciones estructurales reversibles inducidas térmicamente (180-220 K) vinculadas a la transferencia de carga (CT) y el cruce de espín (SCO).
- Las fases ricas en cobalto (6-9) muestran una relajación magnética lenta, con barreras de energía crecientes para la relajación magnética a medida que aumenta el contenido de cobalto.
Conclusiones:
- La relación Co/Fe en estos grupos permite un ajuste sin precedentes de las funcionalidades magnéticas.
- Los enlaces Fe-NC-W facilitan las transiciones de fase, mientras que Co-W CTIST mejora los cambios estructurales y la histeresis magnética.
- Estas soluciones sólidas moleculares basadas en clúster representan una clase única de materiales con comportamientos magnéticos sintonizables para aplicaciones avanzadas.
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