The influence of defects on hydrogen sorption from Mg–V thin films

Abstract

In this paper hydrogen sorption properties of Mg–V multilayer thin films are studied. Thin films are synthesized by means of RF magnetron sputtering. Further modification of material is done using low energy H ion irradiation. The hydrogen sorption properties and kinetics are assessed using TOF-ERDA, in situ optical microscopy coupled with TDS, and TEM analysis. The results of TOF-ERDA indicate full hydrogenation of samples, although the presence of oxygen throughout the film is observed. It corresponds to the formation of MgO, also confirmed by EELS results with hydride plasmon peak hindered by MgO peak. Hydrogenation causes severe damage to the surface of the film and fragmentation of the V layer. TDS and optical analysis indicate lower desorption temperatures for thinner films. The desorption onset does not depend on defects concentration. The kinetic analysis further shows that the apparent activation energy for the thinner film is two times lower.