Hydrogen absorption and desorption in nanocrystalline LaMg2Ni

Hydrogen absorption and desorption properties in LaMg2Ni compound are presented. Nanostructured phases have been obtained by means of ball milling in order to study the influence of the microstructure on the absorption/desorption properties. The structural and hydriding properties were examined by X-ray diffraction, thermal analysis, hydrogen pressure-composition and thermal desorption measurements. Ball milling of as-cast compound gives a significant refinement of the microstructure. Hydrogenation at 443 K leads to the formation of LaMg2NiH7 but at higher temperatures (523 K) LaH2 is produced. Two hours of ball milling promote the formation of LaH2 under hydrogenation at 443 K. Thermal desorption up to 983 K of hydrogenated samples leads again to parent LaMg2Ni phase. (C) 2006 Elsevier B.V. All rights reserved.