Hydrogen in beryllium oxide investigated by DFT: on the relative stability of charged-state atomic versus molecular hydrogen

Abstract

The behavior of hydrogen in perfect wurtzite beryllium oxide is herein investigated by means of electronic structure calculations based on density functional theory. The formation energies of the following set of states of hydrogen (H, H, H, H, [Formula: see text], [Formula: see text]) are computed and their solubility is established as a function of temperature and pressure with emphasis given to conditions relevant for hydrogen-implanted materials. It is found that all magnetic states H, [Formula: see text], [Formula: see text] are unstable, while the relative stability of the non-magnetic states depends on the thermodynamic conditions: H prevails above temperatures around 900 K at standard pressure, which is the lowest temperature in experiments measuring the diffusion coefficient of hydrogen in wurtzite beryllium oxide. Under hydrogen implantation, the total concentration of hydrogen is fixed by the implantation source; it is found that molecular hydrogen prevails starting from a very low total concentration in hydrogen (as low as 10 at.fr.). Finally, the diffusion coefficient of H in beryllium oxide is calculated and the results are compared with previous experimental data.

Interactions of hydrogen with zirconium alloying elements and oxygen vacancies in monoclinic zirconia

“…Still, a few years ago, H2 was found stable with a very narrow range of stability in ZnO [34]. Hodille et al also found molecular hydrogen to be quite stable in BeO [35]. As far as zirconia is concerned, the possibility to have molecular hydrogen has been neglected.…”

Post-mortem analysis of tungsten plasma facing components in tokamaks: Raman microscopy measurements on compact, porous oxide and nitride films and nanoparticles

“…Raman microscopy method gives information about atomic vibrations, and is thus able to distinguish chemical bonds in the solids and to reveal how hydrogen isotopes and impurities are bonded, either to metal atoms or to each other's [33,34]. It is particularly sensitive to detect tungsten oxides and the modifications of their characteristic structure and composition after He or D implantation [35][36][37], as well as to detect the presence of H in oxides [38].…”

Solubility and diffusivity of hydrogen and its isotopes in the BeO system

“…Moreover, as regards the solubility of hydrogen isotopes, the only experimental estimate was carried out on sintered beryllium oxide samples loaded with deuterium 13 . Nevertheless, a few theoretical DFT‐based studies investigated the insertion or diffusion properties of hydrogen in the wurtzite structure 14–17 . The recent work of Hodille 15 extends the work of Marinaupoulos et al 16 .…”

“…Nevertheless, a few theoretical DFT‐based studies investigated the insertion or diffusion properties of hydrogen in the wurtzite structure 14–17 . The recent work of Hodille 15 extends the work of Marinaupoulos et al 16 . by publishing the solution energies for each chemical state of hydrogen (neutral, charged, molecular) but only the diffusion coefficient of molecular hydrogen was evaluated, 15 while the diffusivity of neutral hydrogen was previously computed by Allouche et al 14 .…”

“…The recent work of Hodille 15 extends the work of Marinaupoulos et al 16 . by publishing the solution energies for each chemical state of hydrogen (neutral, charged, molecular) but only the diffusion coefficient of molecular hydrogen was evaluated, 15 while the diffusivity of neutral hydrogen was previously computed by Allouche et al 14 . This work aims at filling the gap in scientific knowledge on the diffusion coefficients of hydrogen isotopes in beryllium oxide by means of DFT computation.…”