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

✍ Scribed by L. Mendoza-Zélis; M. Meyer; L. Baum

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 579 KB
• Volume: 36
• Category: Article
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2010.09.076

✦ Synopsis

Complex ternary hydrides based in Mg and transition metals are very attractive materials for hydrogen and energy storage due to their large volumetric capacity, up to 150 kgH 2 /m 3 in Mg 2 FeH 6 and their high dissociation enthalpies. These compounds may be produced at room temperature by mechanical milling of the constituents in H 2 atmosphere. This technique has also served to explore the synthesis of quaternary hydrides Mg 2 T 1Àz T' z H y , combining two transition metals to optimize the properties of the resulting hydride. In the present work we analyze the mechanical synthesis of the compounds Mg 2 Fe 1Àz Co z H y (z ¼ 0, ¼, ½, 3 /4, 1) by mechanical alloying at room temperature MgeFeeCo powder mixtures in adequate proportion, at 0.3 MPa H 2 . We follow the mechanosynthesis process trough the analysis of the hydrogen absorption kinetic curves. Samples obtained after a steady state was reached were characterized by X ray diffraction and Mo ¨ssbauer spectroscopy. The different stages in the mechanosynthesis of these complex hydrides are discussed in terms of the composition and initial state of the powder mixture.