Structural ordering and dynamics of LaH3-x

T. J. Udovic, Q. Huang, Christof Karmonik, J. J. Rush

Research output: Contribution to journalConference article

10 Scopus citations

Abstract

The structural arrangements, optic-vibrational density of states, and diffusive motions of hydrogen (and deuterium) in the light-rare-earth hydride LaH3-x (for small hydrogen-vacancy fractions x) have been measured by neutron powder diffraction, neutron vibrational spectroscopy, and quasielastic neutron scattering. Diffraction measurements of LaD3-x indicate preparation-dependent changes in structural ordering below room temperature. Vibrational spectra of both pure and isotopically mixed samples reflect the presence of significant H-H interactions involving the hydrogen located in the octahedral and tetrahedral interstices of the fcc metal sublattice. Quasielastic scattering measurements above room temperature reveal two types of hydrogen motions: a localized `rattling' motion of the octahedrally coordinated hydrogen and a long-range diffusional motion via the hydrogen vacancies. A sample color change from black to copperish-orange observed in the vicinity of the highest hydrogen concentrations likely reflects a transition from optical opacity to optical transparency, as reported for LaH3-x thin films.

Original languageEnglish (US)
Pages (from-to)113-117
Number of pages5
JournalJournal of Alloys and Compounds
Volume293
DOIs
StatePublished - Dec 20 1999
EventProceedings of the 1998 International Symposium on Metal-Hydrogen Systems - Fundamentals and Applications (MH98) - Hangzhou, China
Duration: Oct 4 1998Oct 9 1998

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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