Comparative analysis of the hydrogen-vacancy interaction in Mg and Al based on density functional theory

ORAL

Abstract

The interactions of vacancies (V) with atomic hydrogen (H) in the bulk of the metal are expected to play an important role in H-storage as well as H-embrittlement. Using density functional theory we have studied the H-V interactions in hcp-Mg and fcc-Al, two prototypic systems for H storage. We show that a single V can in principle host up to 9 H atoms in Mg and 10 in Al. In going beyond previous theoretical studies we further evaluate the concentration of the H-V complexes for different H loading conditions -- ranging from low pressures to high pressures of H2 gas. We find significant differences between Mg and Al. In the case of Al, up to 15 {\%} of H atoms are trapped in single vacancies even for very low H pressures, which strongly slows down the diffusion of H atoms. In the case of Mg, these trapping effects are negligible for low H pressures. However, vacancies containing multiple H atoms and H-induced superabundant vacancy formation are predicted to occur in Mg at much lower H loading pressures (about 1 GPa) than in Al (about 10 GPa).

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Authors

  • Lars Ismer

    Materials Department, University of California, Santa Barbara, CA 93106-5050

  • Joshua Lusk

    University of New Mexico, Gallup Campus, Sciprint.org, Institute of Gravitation and Cosmology, Moscow, Russia, CSU Long Beach, California State University - East Bay, LLNL, UC Santa Cruz, University of California, Berkeley, Loma Linda Medical University, Northern Illinois University, Santa Cruz Institute for Particle Physics, Dr, Pr, California State University Long Beach, California Polytechnic State University, Department of Physics, California State University, Fresno, NPS, UC-Davis, University of California-Davis, University of California Riverside, Rutgers University, Pomona College, Department of Physics, Imperial College London, Materials Research Laboratory, UC Santa Barbara, Naval Postgraduate School, Whittier College, Cardiff University, Cardiff, Wales - Cardiff School of Biosciences, University of California, Davis - Electrical and Computer Engineering, University of California, Davis - Neurosurgery, Materials Department, University of California, Santa Barbara, CA 93106-5050, Queen's University, Belfast, Rutherford Appleton Laboratory, Technical University of Darmstadt, University of York, University of California, Los Angeles, Kohat University of Science and Technology, Lawrence Livermore National Laboratory, Imperial College, The Blackett Laboratory, University of Strathclyde, University of Oxford, UC Berkeley, UC Berkeley, SLAC, Gesellschaft f\"ur Schwerionenforschung GSI, University of Washington, Seattle, LLNL and XIA LLC, University of Graz, University of California, Davis, Naval Surface Warfare Center-Indian Head Division

  • Joshua Lusk

    University of New Mexico, Gallup Campus, Sciprint.org, Institute of Gravitation and Cosmology, Moscow, Russia, CSU Long Beach, California State University - East Bay, LLNL, UC Santa Cruz, University of California, Berkeley, Loma Linda Medical University, Northern Illinois University, Santa Cruz Institute for Particle Physics, Dr, Pr, California State University Long Beach, California Polytechnic State University, Department of Physics, California State University, Fresno, NPS, UC-Davis, University of California-Davis, University of California Riverside, Rutgers University, Pomona College, Department of Physics, Imperial College London, Materials Research Laboratory, UC Santa Barbara, Naval Postgraduate School, Whittier College, Cardiff University, Cardiff, Wales - Cardiff School of Biosciences, University of California, Davis - Electrical and Computer Engineering, University of California, Davis - Neurosurgery, Materials Department, University of California, Santa Barbara, CA 93106-5050, Queen's University, Belfast, Rutherford Appleton Laboratory, Technical University of Darmstadt, University of York, University of California, Los Angeles, Kohat University of Science and Technology, Lawrence Livermore National Laboratory, Imperial College, The Blackett Laboratory, University of Strathclyde, University of Oxford, UC Berkeley, UC Berkeley, SLAC, Gesellschaft f\"ur Schwerionenforschung GSI, University of Washington, Seattle, LLNL and XIA LLC, University of Graz, University of California, Davis, Naval Surface Warfare Center-Indian Head Division