Identification of vacancy formation sites in LaNi 5Cu during hydrogenation using in situ coincidence doppler broadening technique

Kouji Sakaki, Yumiko Nakamura, Etsuo Akiba

研究成果: ジャーナルへの寄稿学術誌査読

1 被引用数 (Scopus)

抄録

To study the formation mechanism of lattice defects introduced during hydrogenation, we developed equipment that can measure in situ positron lifetime and coincidence Doppler broadening (CDB) simultaneously with pressure-composition (P-C) isotherms at room temperature. The equipment, which consisted of a high-pressure sample holder, reduced the intensity of the background signals in the relatively high momentum region of the Doppler broadening spectrum by more than 2 orders of magnitude in comparison to the background shown by conventional Doppler broadening equipment. Further, the quality of data obtained by our instrument was similar to that obtained from ex situ CDB equipment without a high-pressure sample holder. The substitution effect on the positron annihilation behavior was observed from the ratio curves of CDB spectra for LaNi 5Cu and LaNi 5-xAl x. In addition, using the equipment we developed, we attempted to identify the vacancy formation sites introduced in LaNi 5Cu during hydrogenation. Changes in positron lifetime and the S parameter indicated that the vacancies were introduced above 0.35 H/M during hydrogenation and the introduced vacancies were completely recovered below 0.33 H/M during dehydrogenation. The changes in the ratio curves suggested that vacancies were introduced at Ni sites during hydrogenation.

本文言語英語
ページ(範囲)22238-22244
ページ数7
ジャーナルJournal of Physical Chemistry C
116
42
DOI
出版ステータス出版済み - 10月 25 2012

!!!All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • エネルギー一般
  • 物理化学および理論化学
  • 表面、皮膜および薄膜

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