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Issue 13, 2011
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Intrinsic defects and dopants in LiNH2: a first-principles study

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Abstract

The lithium amide (LiNH2) + lithium hydride (LiH) system is one of the most attractive light-weight materials options for hydrogen storage. Its dehydrogenation involves mass transport in the bulk (amide) crystal through lattice defects. We present a first-principles study of native point defects and dopants in LiNH2 using density functional theory. We find that both Li-related defects (the positive interstitial Li+i and the negative vacancy VLi) and H-related defects (H+i and VH) are charged. Li-related defects are most abundant. Having diffusion barriers of 0.3–0.5 eV, they diffuse rapidly at moderate temperatures. VH corresponds to the [NH]2 ion. It is the dominant species available for proton transport with a diffusion barrier of ∼0.7 eV. The equilibrium concentration of H+i, which corresponds to the NH3 molecule, is negligible in bulk LiNH2. Dopants such as Ti and Sc do not affect the concentration of intrinsic defects, whereas Mg and Ca can alter it by a moderate amount. Ti and Mg are easily incorporated into the LiNH2 lattice, which may affect the crystal morphology on the nano-scale.

Graphical abstract: Intrinsic defects and dopants in LiNH2: a first-principles study

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Publication details

The article was received on 18 Aug 2010, accepted on 14 Jan 2011 and first published on 22 Feb 2011


Article type: Paper
DOI: 10.1039/C0CP01540G
Citation: Phys. Chem. Chem. Phys., 2011,13, 6043-6052
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    Intrinsic defects and dopants in LiNH2: a first-principles study

    E. Hazrati, G. Brocks, B. Buurman, R. A. de Groot and G. A. de Wijs, Phys. Chem. Chem. Phys., 2011, 13, 6043
    DOI: 10.1039/C0CP01540G

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