First-Principles Study of hydrogen retention and diffusion in beryllium oxide

In the quest of new renewable sources of energy, hydrogen is a promising candidate and its storage in solid-state materials is of extreme importance. Beryllium has been invoked in the past for this purpose because of its low density, and for the rather low energy of adsorption and retention of hydrogen that makes its restitution relatively easy, therefore it seems interesting to also investigate the properties of beryllium oxide. Hydrogen (and its isotopes) is also important as the fuel of deuterium-tritium plasma in tokamaks for energy production by magnetically confined nuclear fusion, when the plasma is in interaction with the beryllium (and beryllium oxide) of the inner walls of the device. Another interest of beryllium oxide (BeO) lies in its properties as a ceramic: high thermal conductivity, high electric resistivity, efficient accumulation of energy, and transparency to a large spectrum of radiations. The bad point is that beryllium oxide grows very easily as a film on pure beryllium sample and significantly perturbs the material properties on the surface in a manner that is not easy to comprehend. The dynamics of hydrogen atom retention in beryllium oxide implies the knowledge of its interactions of the atoms constituting the material, on the surface and in the bulk and in the defects present into this media. These defects can be native or generated by the hydrogen beam. This paper proposes a detailed calculation of energy trapping and diffusivity of interstitial atoms (hydrogen, beryllium, oxygen). Then the same kind of computations is described for atomic vacancies and the trapping of hydrogen atoms into these vacancies. The last step deals with the surfaces of beryllium oxide, their structures and reactivity to hydrogen. (C) 2015 Elsevier B.V. All rights reserved.