Tunable Hydrogen Storage in Magnesium - Transition Metal Compounds

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dc.creatorEr, Suleyman
dc.creatorTiwari, Dhirendra
dc.creatorde Wijs, Gilles A.
dc.creatorBrocks, Geert
dc.date2008-10-13
dc.date.accessioned2026-07-07T12:37:10Z
dc.date.available2026-07-07T12:37:10Z
dc.descriptionMagnesium dihydride ($\mgh$) stores 7.7 weight % hydrogen, but it suffers from a high thermodynamic stability and slow (de)hydrogenation kinetics. Alloying Mg with lightweight transition metals (TM = Sc, Ti, V, Cr) aims at improving the thermodynamic and kinetic properties. We study the structure and stability of Mg$_x$TM$_{1-x}$H$_2$ compounds, $x=[0$-1], by first-principles calculations at the level of density functional theory. We find that the experimentally observed sharp decrease in hydrogenation rates for $x\gtrsim0.8$ correlates with a phase transition of Mg$_x$TM$_{1-x}$H$_2$ from a fluorite to a rutile phase. The stability of these compounds decreases along the series Sc, Ti, V, Cr. Varying the transition metal (TM) and the composition $x$, the formation enthalpy of Mg$_x$TM$_{1-x}$H$_2$ can be tuned over the substantial range 0-2 eV/f.u. Assuming however that the alloy Mg$_x$TM$_{1-x}$ does not decompose upon dehydrogenation, the enthalpy associated with reversible hydrogenation of compounds with a high magnesium content ($x=0.75$) is close to that of pure Mg.
dc.description8 pages, 5 figures
dc.identifierhttps://arxiv.org/abs/0810.2254
dc.identifierhttp://arxiv.org/abs/0810.2254
dc.identifierPhys. Rev. B 79, 024105 (2009)
dc.identifierdoi:10.1103/PhysRevB.79.024105
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/218348
dc.subjectMaterials Science
dc.titleTunable Hydrogen Storage in Magnesium - Transition Metal Compounds
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