Hydrogenation of Pd-capped Mg thin films prepared by DC magnetron sputtering

Structural and optical properties of pure Mg thin film coated with Pd have been investigated. Pd-capped Mg thin films had been prepared by DC magnetron sputtering. This work presents an ex situ study on hydrogenation and dehydrogenation kinetics of Pd/Mg films at different conditions using XRD, AFM and optical spectrophotometer. We have succeeded to load thin films of Mg to MgH2 at normal temperature and normal pressure of hydrogen gas. In hydrogenation, α-MgH2 phase of magnesium hydride was observed in hydrogenated films at 200 °C and γ-MgH2 at 250 °C respectively. The desorption kinetics in vacuum also revealed the phase transformation α-MgH2 to γ-MgH2. A reflectance change was observed in hydrogenated films in comparison of as deposited thin film. Hydrogenated (H loaded) samples were observed partially transparent in comparison of as deposited.

Research highlights► Ex situ study of the hydrogenation/dehydrogenation of Pd-capped Mg thin films. ► Desorption kinetics in vacuum revealed the phase transformation α-MgH2 to γ-MgH2 at 250 °C. ► Hydrogenated (H loaded) samples were observed partially transparent in comparison of as deposited. ► Thus switchable mirror properties were obtained in Pd-capped Mg film.