Ab initio calculations and statistical mechanics are combined to elucidate the thermodynamics of H vacancies in MgH2. A general method based on a grand-canonical ensemble of defect configurations is presented to model the exchange of hydrogen between crystalline MgH2 and gas-phase H2. We find that, even at the lowest hydrogen partial pressures at which the hydride phase is stable, MgH2 is capable of accommodating only very small concentrations of hydrogen vacancies. These vacancies are mainly isolated rather than forming clusters, contrary to what is expected from a simple energetic analysis.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Nov 25 2009|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics