We focus on the H-2 desorption properties of the 2NaBH(4) + MgH2 system destabilized by different methods. Nanostructured powder mixtures were prepared by ball milling the starting hydrides and nanoconfined reactive composites were obtained by melting infiltration of the hydrides into a Si-based SBA-15 support. NbF5 was tested as catalyst in both the preparations.Structural characterization by X Ray Diffraction and Transmission Electron Microscopy allowed evaluating the successful synthesis of SBA15 matrix, the microstructural features of ball milled and nanoconfined hydrides as well as the success of infiltration process. The evaluation of the sorption properties, by manometric Sievert-type apparatus and thermal desorption spectroscopy, revealed the efficiency of the hydride destabilization, obtained by the different routes, in decreasing the hydrogen release temperature and improving desorption kinetics. (c) 2012 Elsevier B.V. All rights reserved.

A new method is proposed for estimating the enthalpies of formation of ${L1}_{2}$ (fcc-ordered) intermetallics from the heat release measured during ordering of their disordered polymorphs. The method is applied to C${\mathrm{u}}_{3}$Au, N${\mathrm{i}}_{3}$Al, and N${\mathrm{i}}_{3}$Si. The resulting estimates of enthalpies of formation are close to values obtained by high temperature dissolution calorimetry. They also appear to be more precise than estimates based on Miedema's correlations provided that care is taken to account properly for the magnetic and lattice stability contributions to the formation enthalpies in the ordered and disordered states.