Study of the hydrogenation/dehydrogenation processes of ZrCr0.7Ni1.3, a Laves phase-rich multi-component system, by in-situ neutron diffraction underhydrogen gas pressure

Powder neutron diffraction phase analyses were performed on a ZrCr0.7Ni1.3 sample by using the Rietveld method. The average phase proportions are 59% C15-Laves phase, 36% Zr7Ni10 and 5% elemental free chromium. In-situ neutro n diffraction experiments were performed at 323 K under deuterium pressure. Cyclic refinements were carried out on the data recorded during both the a bsorption and desorption cycles. A non-reversible amount of absorbed hydrog en was found to be stored by the minor Zr7Ni10 phase. After complete hydrog enation, the Zr7Ni10 phase was found to transform into an amorphous phase, accompanying the overall reduction of reversible hydrogen capacity of the m aterial. (C) 2001 Elsevier Science B.V. All rights reserved.