Thermodynamics of hydrogen vacancies inMgH2from first-principles calculations and grand-canonical statistical mechanics

R. Grau-Crespo, K. C. Smith, T. S. Fisher, N. H. de Leeuw, U. V. Waghmare
2009 Physical Review B  
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 introduced to model the exchange of hydrogen between crystalline MgH2 and gas-phase H2. We find that, at temperatures and hydrogen partial pressures of practical interest, MgH2 is capable of accommodating only very small concentrations of hydrogen vacancies, which consist mainly of isolated defects
more » ... ather than vacancy clusters, contrary to what is expected from a simple energetic analysis.
doi:10.1103/physrevb.80.174117 fatcat:kd3sutnhgnfadmuwrjcqzbivxm