NMR study of a temperature-induced structural transition in ZrBe 2D x

Vikram Kodibagkar, Julie L. Herberg, Robert C. Bowman, Mark S. Conradi

Research output: Contribution to journalConference articlepeer-review

6 Scopus citations

Abstract

We have studied the motion of D atoms in ZrBe 2D 1.56 and ZrBe 2D 1.4 using deuterium NMR and observed a temperature-induced structural transition near 240 K. By comparing the behavior of hydride and deuteride samples with the same concentration (x=1.4), the absence of a transition in the hydride is shown to be an isotope effect. Above 240 K, the deuterium relaxation times T 1 and T 2 behave as expected from proton data in ZrBe 2H 1.4. However, on decreasing the temperature below 240 K, T 2 decreases rapidly and T 1 increases rapidly, indicating that the D atom mobility is dramatically reduced. Above the transition temperature, the spectrum shows a quadrupolar doublet splitting of order 1 kHz, reflecting a small motionally averaged electric field-gradient (EFG) at the D atoms. Upon cooling below 240 K the line broadens rapidly, revealing a large distribution of quadrupolar splittings and EFGs at the individual sites. Thus substantial variations exist between the D-atom sites, despite their nominal equivalence in the neutron diffraction-determined structure. We suggest that the strong Be-H (Be-D) repulsion generates substantial Be displacements near vacant D-atom sites. The probable nature of the transition is discussed from the point of view of ordering of D-atom vacancies.

Original languageEnglish (US)
Pages (from-to)179-182
Number of pages4
JournalJournal of Alloys and Compounds
Volume330-332
DOIs
StatePublished - Jan 17 2002
Externally publishedYes
EventProceedings of the International Symposium on Metal-Hydrogen (MH 2000) - Noosa Heads, QLD, Australia
Duration: Oct 1 2000Oct 6 2000

Keywords

  • Deuterium
  • Diffusion
  • Intermetallic compound
  • Isotope effect
  • NMR
  • Structural transition
  • Two-dimensional diffusion

ASJC Scopus subject areas

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

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