Abstract

ITURBE-GARCIA, J.L.; LOPEZ-MUNOZ, B.E.; BASURTO, R.  and  MILLAN, S.. Hydrogen desorption process in Mg₂Ni hydrides. Rev. mex. fis. [online]. 2006, vol.52, n.4, pp.365-367. ISSN 0035-001X.

One of the most interesting intermetallic compounds investigated for energy storage purposes has been the Mg₂Ni alloy which was prepared by mechanical alloying. Hence it was used here for hydriding-dehydriding implied mechanisms studies. Hydrogenation of milling prepared Mg₂Ni alloy samples under a 1 MPa H₂ flux at 473K for 5 min allowed the formation of two Mg₂Ni-hydrides which were identified by the empirical formulae Mg₂NiH₄ and Mg₂NiH_0.3[1]. Dehydriding behavior along the temperature range from 298 to 623K was recorded by Thermo Gravimetric Analysis (TGA). TGA spectrum exhibited two weight decrease peaks. The maximum hydrogen amount desorbed was 3.95 ± 0.01 wt%. Isotherms between 470 and 600K, every 30K, were obtained by using the same technique, showing a discontinuity which might be associated with a dehydriding process taking place in two steps. Approximately 40-50% of the total H₂ content seems to be desorbed in the first faster step. The present results might confirm that the two hydrides formed present a differentiated desorption outline.

Keywords : Mg₂Ni alloy; hydriding/dehydriding; hydrogen storage material; dehydriding rates; intermetallic hydrides; hidrogenación/deshidrogenación; hidrógeno almacenado; tasa de deshidrogenación.