Complex quaternary hydrides Mg2(Fe,Co)Hy for hydrogen storage

LUIS MENDOZA ZELIS; MARCOS MEYER; LORENA BAUM

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2011 vol. 36 p. 600 - 605

0360-3199

Complex ternary hydrides based in Mg and transition metals are very attractive materialsfor hydrogen and energy storage due to their large volumetric capacity, up to 150 kgH2/m3in Mg2FeH6 and their high dissociation enthalpies. These compounds may be produced atroom temperature by mechanical milling of the constituents in H2 atmosphere. Thistechnique has also served to explore the synthesis of quaternary hydrides Mg2T1-zT’zHy,combining two transition metals to optimize the properties of the resulting hydride. In thepresent work we analyze the mechanical synthesis of the compounds Mg2Fe1-zCozHy(z ¼ 0, ¼, ½, 3/4, 1) by mechanical alloying at room temperature MgeFeeCo powder mixturesin adequate proportion, at 0.3 MPa H2. We follow the mechanosynthesis process trough theanalysis of the hydrogen absorption kinetic curves. Samples obtained after a steady statewas reached were characterized by X ray diffraction and Mo¨ ssbauer spectroscopy. Thedifferent stages in the mechanosynthesis of these complex hydrides are discussed in termsof the composition and initial state of the powder mixture.