Unusual Volume Reduction in CaLi<sub>2-x</sub>Mg<sub>x</sub> by Hydrogen Uptake

DOI

説明

To understand the hydrogen storage properties of CaLi2-xMgx having a C14 Laves phase structure, changes in its average and local structures by hydrogenation were investigated by using the Rietveld and the atomic pair distribution function analyses of X-ray diffraction data. We found that after hydrogen uptake at 283 K, Mg-containing samples exhibit a C14 phase with reduced volume. This C14 phase readily decomposes into CaH2 at temperatures higher than 300 K. Our study suggests that hydrogen absorption in CaLi2-xMgx at 283 K is multi-step reaction. Lithium that can easily diffuse through C14 crystals reacts with hydrogen forming a Li-rich hydride phase. On the other hand, slow diffusion of large Ca atoms and strong Mg-Mg and Mg-Ca interaction restrain the immediate formation of CaH2. As a result, there is a substantial time lag between the formation of a Li-rich hydride phase and the formation of CaH2 at 283 K. This brings about a C14 phase with reduced volume where a large number of Li vacancies are present immediately after hydrogenation.

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詳細情報 詳細情報について

  • CRID
    1391131406306188288
  • NII論文ID
    130007969643
  • DOI
    10.18957/rr.8.1.17
  • ISSN
    21876886
  • 本文言語コード
    en
  • データソース種別
    • JaLC
    • CiNii Articles
  • 抄録ライセンスフラグ
    使用不可

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