Formation of superabundant vacancies in Pd-H alloys

Yuh Fukai, Yasuyuki Ishii, Yoshihiro Goto, Kuniaki Watanabe

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

Temporal variation of the lattice parameter of Pd was measured under high hydrogen pressures (2-5 GPa) and temperatures (672-896 °C) by X-ray diffraction using a synchrotron radiation, and observed lattice contraction was interpreted as being due to the formation of a large number of vacancy-hydrogen (Vac-H) clusters, i.e. superabundant vacancies. Analysis of the result led to the conclusion that a major part of Vac-H clusters (amounting to approximately 10 at.%) were introduced by diffusion from the surface, after a small number of them had been formed at some internal sources. The thermal-equilibrium concentration of Vac-H clusters at high temperatures shows a saturation behavior, which indicates the presence of a maximum possible concentration (ca. 16 at.%) of the clusters. The formation energy, entropy and volume of a Vac-H cluster are found to be 0.72 eV, 7.2 k and 0.60 Ω, respectively, and the migration energy and volume are 1.20 eV and 0.49 Ω, respectively. Various other implications of the results are also discussed.

Original languageEnglish
Pages (from-to)121-132
Number of pages12
JournalJournal of Alloys and Compounds
Volume313
Issue number1-2
DOIs
Publication statusPublished - 2000 Dec 15
Externally publishedYes

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Vacancies
Hydrogen
Synchrotron radiation
Lattice constants
Entropy
X ray diffraction
Temperature

ASJC Scopus subject areas

  • Metals and Alloys

Cite this

Formation of superabundant vacancies in Pd-H alloys. / Fukai, Yuh; Ishii, Yasuyuki; Goto, Yoshihiro; Watanabe, Kuniaki.

In: Journal of Alloys and Compounds, Vol. 313, No. 1-2, 15.12.2000, p. 121-132.

Research output: Contribution to journalArticle

Fukai, Yuh ; Ishii, Yasuyuki ; Goto, Yoshihiro ; Watanabe, Kuniaki. / Formation of superabundant vacancies in Pd-H alloys. In: Journal of Alloys and Compounds. 2000 ; Vol. 313, No. 1-2. pp. 121-132.
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