Investigation of Mg-Ti thin films hydriding kinetics

Abstract

Magnesium hydride is a promising material for hydrogen storage but the slow hydriding and dehydriding kinetics limit its practical application. Identification of effective catalyst is a subject of great interest in developing MgH2 system as a potential hydrogen storage medium. A thin layer of Ti acts as a catalyst. The main emphasis of this study was to investigate Mg-Ti-H system hydrogenation properties. For this purpose nanocrystalline Mg-Ti films were deposited onto quartz substrates using magnetron co-sputtering technique and hydrogenated at 10 bar H2 pressure in the temperature range from 200 up to 300 °C during 6 h. The synthesised samples were characterized by X-ray diffraction, and surface morphology were observed by means of scanning electron microscopy (SEM).The experimental results show that the growth of the initial hydride layer may be blocked by the surface oxide barrier layer formed during hydrogenation. The growing hydride phase in the bulk generates stresses that induce cracks and holes in the oxide barrier formed during the initial stages of hydrogenation, and hydrogen release.