Effect of interfacial free energy on hydriding reaction of Mg-Ni thin films

摘要

The Mg_(2.9)Ni film with preferential orientated nanocrystalline structure was obtained by magnetron sputtering. The hydrogen storage properties and microstructure were investigated by pressure-composition-isotherms measurement, x-ray diffraction and transmission electron microscopy. A reversible hydrogen storage content of about 4.45 mass % at 497 K has been obtained. The preferential orientation of the deposited film was destroyed after only one hydrogenation/dehydrogenation cycle. Both experiment and simplified calculation results proved that the hydrogenation/dehydrogenation reaction temperature decreases due to the extra interfacial free energy stored in the boundary, which demonstrate that Mg based hydride can be substantially destabilized by inducing nanocrystalline structure.