Defect volume for Schottky defect formation and cation vacancy migration in LiH

Symeonides, Chrysoleon I.

doi:10.1016/j.jallcom.2008.12.026

Cited by 4 publications

(1 citation statement)

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“…The formation and migration of such defects are known to cause volume expansion in alkali metal halides. 32 Recently, Symeonides 33 calculated that the formation of Schottky pairs in LiH is accompanied by an increase in cell volume as the lattice rearranges around the defect site. We are able to observe this microstructural effect due to the presence of an excess equivalent of lithium hydride from the hydrogenation of Li 3 N. In the isolated LiNH 2 -Li 2 NH system, all of the lithium hydride is consumed during dehydrogenation.…”

Section: Processmentioning

confidence: 99%

In situ X-ray powder diffraction studies of hydrogen storage and release in the Li–N–H system

Makepeace

Jones

Callear

et al. 2014

Phys. Chem. Chem. Phys.

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We report the experimental investigation of hydrogen storage and release in the lithium amide-lithium hydride composite (Li-N-H) system. Investigation of hydrogenation and dehydrogenation reactions of the system through in situ synchrotron X-ray powder diffraction experiments allowed for the observation of the formation and evolution of non-stoichiometric intermediate species of the form Li1+xNH2-x. This result is consistent with the proposed Frenkel-defect mechanism for these reactions. We observed capacity loss with decreasing temperature through decreased levels of lithium-rich (0.7 ≤ x ≤ 1.0) non-stoichiometric phases in the dehydrogenated material, but only minor changes due to multiple cycles at the same temperature. Annealing of dehydrogenated samples reveals the reduced stability of intermediate stoichiometry values (0.4 ≤ x ≤ 0.7) compared with the end member species: lithium amide (LiNH2) and lithium imide (Li2NH). Our results highlight the central role of ionic mobility in understanding temperature limitations, capacity loss and facile reversibility of the Li-N-H system.

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Section: Processmentioning

confidence: 99%