Comparative study on hydrogenation properties of Pd capped Mg and Mg/Al films

摘要

Recent emergence of Mg as a promising hydrogen storage material with 7.6 wt% hydrogen encourages study on its thin films to understand physics of storage mechanism. The present study investigates the variations in hydrogen storage properties of Pd sandwiched Mg films upon introduction of Al layer. Multilayered stack of Pd/Mg/Pd and Pd/Al/Mg/Pd were grown on Si substrate using vapor deposition method and further hydrogenated at 150° C under 2 bar H_2 pressure for 2 h. Elastic Recoil Detection Analysis (ERDA) technique with 120 MeV Ag~(9+) ions was used to obtain hydrogen concentration versus incident ion fluence. ERDA study reveals that Pd/Mg/Al/Pd films absorb 6.01 × 10~(18)hydrogen atoms/cm~2 in comparison to 4 × 10~(17) atoms/cm~2 absorbed by Pd/Mg/Pd system. Atomic force Microscopy (AFM) and X-ray Diffraction (XRD) techniques were utilized to analyze the morphological and structural changes in the hydrogenated films. Results indicate that addition of Al to the base system has led to the formation of Mg(AlH_4)_2 along with MgH_2 causing an increment in the hydrogen storage capacity and reduction in the oxygen content.