NMR studies of hydrogen motion in nanostructured hydrogen-graphite systems

G. Majer, E. Stanik, S. Orimo

Research output: Contribution to journalConference articlepeer-review

27 Citations (Scopus)

Abstract

Nanostructured hydrogen-graphite systems, CnanoHx (x = 0.24, 0.31, 0.96), have been characterized by first nuclear magnetic resonance (NMR) measurements. The NMR spectrum of CnanoH0.96 is well represented by the sum of a Lorentzian and a Gaussian line, indicating two types of hydrogen coordinations. These two components may be ascribed to hydrogen in graphite interlayers and hydrogen chemisorbed at dangling bonds. Information on the hydrogen hopping frequencies is provided by the spin-lattice relaxation rate Γ1. The temperature dependence of Γ1 yields high hydrogen diffusivities and low activation energies of Ea ≈ 0.1 eV. A change in the Γ1 data of CnanoHx with x=0.24 and 0.31 occurred after the samples had been heated to about 400-430 K. This suggests that in this temperature range hydrogen atoms start to occupy sites with different site energies, resulting in a distribution of the activation energies for hydrogen motion.

Original languageEnglish
Pages (from-to)617-621
Number of pages5
JournalJournal of Alloys and Compounds
Volume356-357
DOIs
Publication statusPublished - 2003 Aug 11
Externally publishedYes
EventProceedings of the Eight International Symposium on Metal Hyd (MH 2002) - Annecy, France
Duration: 2002 Sep 22002 Sep 6

Keywords

  • H motion
  • NMR
  • Nanostructured graphite
  • Spin-lattice relaxation

ASJC Scopus subject areas

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

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