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Los hidratos de galio polianiónicos de los precursores del tipo AlB2 AeGaE (Ae = Ca, Sr, Ba; E = Si, Ge, Sn)
Michael J Evans1, Gregory P Holland, Francisco J Garcia-Garcia
1Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, USA.
Journal of the American Chemical Society
|August 14, 2008
Resumen
Nuevos hidritos cuaternarios como el SrGaGeH fueron sintetizados a partir de compuestos intermetálicos. Estos materiales exhiben una transición reversible entre metal y no metal y cuentan con una estructura única de polianiones 2D, con aplicaciones potenciales en la ciencia de los materiales.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química del estado sólido.
- Química Inorgánica La Química Inorgánica es la química inorgánica.
Sus antecedentes:
- Se ha investigado el comportamiento de hidrogenación de metales de tierra alcalina (Ae) - gallio (Ga) - pnictógeno (E) y compuestos intermetálicos (Ae = Ca, Sr, Ba; E = Si, Ge, Sn).
- Las fases precursoras AeGaE exhiben propiedades metálicas y se cristalizan en el tipo de estructura AlB2 o sus variantes.
Objetivo del estudio:
- Sintetice y caracterice estructuralmente los nuevos hidritos cuaternarios (deuteridas) de la fórmula AeGaEH(D).
- Explore las propiedades electrónicas y las características de almacenamiento de hidrógeno de estos nuevos grupos principales de hidruros metálicos/semimetales.
Principales métodos:
- Síntesis a través de la hidrogenación de los precursores intermetálicos.
- Caracterización estructural utilizando difracción de rayos X en polvo, difracción de neutrones y espectroscopia de estado sólido (1) H NMR.
- Análisis de propiedades electrónicas a través de la determinación de la brecha de banda.
Principales resultados:
- Se obtuvieron con éxito SrGaGeH (D), BaGaSiH (D), BaGaGeH (D) y BaGaSnH (D).
- Estos hidruros se cristalizan en el tipo de estructura trigonal SrAlSiH, con un 2D [GaEH](2-) polianión.
- Exhibieron brechas de banda pequeña (0.1-0.6 eV), lo que indica una transición metal-no-metal después de la hidrogenación.
- Se observó una transición reversible de metal a no metal para SrGaGe, BaGaSi y BaGaGe; BaGaSnH mostró una descomposición parcial tras la liberación de hidrógeno.
- Temperaturas altas de desorción de hidrógeno (>400 °C).
Conclusiones:
- Los hidruros cuaternarios sintetizados representan una nueva clase de compuestos metálicos/semimetales del grupo principal.
- La estructura del polianión [GaEH](2-) y las propiedades electrónicas resultantes son características clave.
- La reversibilidad de la transición metal-no-metal sugiere potencial para aplicaciones relacionadas con el hidrógeno.
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