Mechanically alloyed Mg-Fe-Ti powder mixtures as Hydrogen reservoirs.

M. MEYER; L. A. MENDOZA ZÉLIS

Gijon

Simposio; ISMANAM INternational Symposium on Metastable, Amorphous and Nanocrystalline Materials; 2011

Following recently reported research [1] on Mg-Fe-Ti films with remarkable hydrogen sorption properties, we attempted an investigation on mechanically alloyed powder mixtures of identical composition. We milled samples of nominal composition Mg80Fe10Ti10, Mg70Fe15Ti15 and Mg60Fe20Ti20 in H2 ambient, till a steady state with no further H2 absorption was attained. The resulting powders were then characterized and submitted to several discharge-charge cycles. We extend our investigation to samples of nominal composition Mg69Fe26Ti5, Mg64Fe26Ti10 and Mg64Fe31Ti5 in order to also explore a compositional region with reported [2] optimal sorption properties for similar Mg-Ni-Ti films. Each milled sample was dynamically discharged (charged) by increasing (decreasing) the temperature at a given starting H2 pressure. The resulting curves were analyzed to extract approximate values of the equilibrium (T,P) data for H2 desorption (absorption). All the samples were characterized by X ray diffraction and Mössbauer spectroscopy on 57Fe, before and after their cycling in H2. The results were analyzed in the framework of possible mechanisms for the transition metals catalytic action on the H2 sorption processes and the influence of the sample microstructure.  [1] B. Zahiri, C. Harrower, B.S. Amirkhiz, D. Mitlin, Applied Phys. Lett. 95 (2009) 103114. [2] R. Gremaud, C. Broedersz, D. Borsa, A. Borgschulte, P. Mauron, H. Schreuders, J. Rector, B. Dam, R. Griessen, Adv. Mater. 19 (2007) 2813