(221e) Storing Hydrogen Using (Ti,V)-Based Bcc Materials

Light vanadium-based alloys crystallizing in the body centered cubic (bcc) structure are promising materials for hydrogen storage. Adding titanium to vanadium improves the kinetics of the hydrogen absorption whereas addition of 3d metals such as iron enhances the reversible absorption capacity [1] and the activation process. The aim of this study is to highlight the influence of alloy composition on the hydrogenation properties (absorption pressure and capacity) of the bcc phase. The isothermal sections at 1000 °C and 1200 °C of the Ti?V?Fe system have been experimentally studied to get a better understanding of the bcc-region boundaries and equilibrium phases. For iron contents below 15 at.%, the isotherm at 1000 °C shows that the bcc phase is the only stable one. Moreover, our results indicate that the ternary extension of the TiFe2 phase with the C14 structure reaches the composition Ti33V33Fe33 [2]. The pressure-composition absorption isotherms of several bcc-alloys of the Ti?V?Fe system have been measured at various temperatures. For a constant Ti/V ratio, addition of iron increases the plateau pressure, as well as addition of vanadium for a given Ti/Fe ratio. The dependence of the capacity on the alloy composition will also be discussed

[1] S. Challet, M. Latroche, and F. Heurtaux, J. Alloys Compd., 439, 294, 2007. [2] B. Massicot, J.-M. Joubert and M. Latroche, Int. J. Mater. Res., submitted (2010).