Thermodynamics of hydrogen vacancies in MgH2 from first-principles calculations and grand-canonical statistical mechanics

R. Grau-Crespo, K. C. Smith, T. S. Fisher, N. H. De Leeuw, U. V. Waghmare

Research output: Contribution to journalArticle

Abstract

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 languageEnglish (US)
Article number174117
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume80
Issue number17
DOIs
StatePublished - Nov 25 2009
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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