Hydrogen absorption in magnesium based crystalline thin films

A study is carried out for hydrogenation of Mg based thin films produced via thermal evaporation. Films produced were pure Mg, Mg capped with Au–Pd, Mg–Cu co-deposited and Mg–Cu multilayered. The films under the experimental conditions employed were crystalline with columnar grains with some degree of preferred orientation. In multi-component systems, the films in the as-deposited state were made of individual elements, but upon hydrogenation at temperatures greater than 473 K, the elements react with each other yielding the intermetallic phases. The study showed that, of the systems studied in this work, Mg–Cu multilayer yielded the most favorable result as useful storage system, for Mg portion of the film can be converted totally into MgH2MgH2, this occurring at temperatures not greater than 473 K. The study implies that if the as-deposited structure were to be used and preserved as hydrogen storage medium, there is a narrow temperature window for hydrogenation.