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

Grau-Crespo, R; Smith, KC; Fisher, TS; de Leeuw, NH; Waghmare, UV; (2009) Thermodynamics of hydrogen vacancies in MgH2 from first-principles calculations and grand-canonical statistical mechanics. PHYS REV B , 80 (17) , Article 174117. 10.1103/PhysRevB.80.174117.

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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 H-2. 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.

Type:Article
Title:Thermodynamics of hydrogen vacancies in MgH2 from first-principles calculations and grand-canonical statistical mechanics
DOI:10.1103/PhysRevB.80.174117
Keywords:ab initio calculations, hydrogen, hydrogen storage, magnesium compounds, statistical mechanics, thermodynamics, vacancies (crystal), AUGMENTED-WAVE METHOD, MAGNESIUM HYDRIDE, KINETICS, STORAGE, SURFACE, FESBO4, SYSTEM
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

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