Behavior of hydrogen ions, atoms, and molecules in alpha-boron studied using density functional calculations

We examine the behaviour of hydrogen ions, atoms and molecules in alpha-boron using density functional calculations. Hydrogen behaves as a negative-U centre, with positive H ions preferring to sit off-center on inter-layer bonds and negative H ions sitting preferably at in-plane sites between three...

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Bibliographic Details
Published inarXiv.org
Main Authors Wagner, Philipp, Ewels, Christopher P, Suarez-Martinez, Irene, Guiot, Vincent, Cox, Stephen F J, Lord, James S, Briddon, Patrick R
Format Paper Journal Article
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 17.03.2011
Subjects
Boron
Cages
Density
Diffusion barriers
Hydrogen
Hydrogen atoms
Hydrogen ions
Icosahedrons
Implantation
Mathematical analysis
Physics - Materials Science
Physics - Other Condensed Matter
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Summary:We examine the behaviour of hydrogen ions, atoms and molecules in alpha-boron using density functional calculations. Hydrogen behaves as a negative-U centre, with positive H ions preferring to sit off-center on inter-layer bonds and negative H ions sitting preferably at in-plane sites between three B12 icosahedra. Hydrogen atoms inside B12 icosahedral cages are unstable, drifting off-center and leaving the cage with only a 0.09 eV barrier. While H0 is extremely mobile (diffusion barrier 0.25 eV), H+ and H- have higher diffusion barriers of 0.9 eV. Once mobile these defects will combine, forming H2 in the interstitial void space, which will remain trapped in the lattice until high temperatures. Based on these results we discuss potential differences for hydrogen behaviour in beta-boron, and compare with experimental muon-implantation data.
ISSN:2331-8422
DOI:10.48550/arxiv.1103.3374