HYDROGEN ABSORPTION-DESORPTION IN 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 in the absorption/desorption properties. The structural and hydriding properties were examined by X-ray diffraction, thermal analysis, hydrogen pressure-composition isotherms and thermal desorption measurements. Ball milling of as-cast alloy gives a significant refinement of the microstructure. Hydrogenation at 170 °C leads to the formation of LaMg₂NiH₇. Treatments at higher temperatures (250 °C) lead to the formation of LaH₂. Thermal desorption up to 710 °C of hydrogenated phases leads again to parent LaMg₂Ni phase.