In-situ desorption of magnesium hydride irradiated and non-irradiated thin films: Relation to optical properties

Abstract

Processes taking place during hydrogen desorption from MgH2 thin films were investigated in as-prepared samples and samples modified by argon ion irradiation. Irradiation was used to produce well-defined defects with depth distribution. It was shown that the size, shape, and concentration of Mg nuclei formed during hydrogen desorption from MgH2 thin films depend on the characteristics and distribution of the induced defects. In as-prepared samples the shape of Mg nuclei is spherical, while in irradiated samples, it is highly irregular. Variations in sample colour were observed during hydrogen desorption and before the creation of Mg nuclei. DFT calculations showed that the observed variations in the optical properties of samples can be explained by changes in MgH2 electronic structure -the appearance of an H-vacancy band within the MgH2 energy gap. (C) 2016 Elsevier B.V. All rights reserved.