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Scientific article
English

A Structural Study of the Homogeneity Domain of LaNi5

Contributors

Joubert, Jean-Marc Eric; Cerny, Radovan; Latroche, M.; Leroy, E.; Guenee, Laure; Percheron-Guégan, A.; Yvon, Klaus

Published in

Journal of solid state chemistry, vol. 166, no. 1, p. 1-6

Publication date

2002

Abstract

LaNi5 is a very important intermetallic compound for hydrogen storage applications. Its homogeneity range at 1200°C has been investigated by single-crystal X-ray diffraction, electron probe microanalysis, and mass density measurements. At the nickel-rich end the hexagonal structure (CaCu5 type) extends to the composition LaNi5.45. The excess of nickel is accommodated by random substitutions of lanthanum atoms by nickel dumbbells and by displacements of nickel atoms which are presumably correlated with the La atom substitutions. Interatomic distances suggest that the Ni atom displacements occur in directions toward vacant La atom sites, i.e., toward the center of Ni dumbbells. At the nickel-poor end the structure extends to the composition LaNi4.88. The excess of lanthanum is presumably accommodated by the simultaneous occurrence of lanthanum atoms and vacancies on nickel atom sites. Both models are consistent with mass density and electron probe microanalysis measurements. Hydrogenation thermodynamic properties have been measured as a function of composition.

Keywords

  • Intermetallics
  • Hydrides
  • LaNi5
  • Crystal structure
  • EPMA
  • Nonstoichiometry.

UNIGE affiliation entities

UNIGE research groups

Citation (ISO format)

JOUBERT, Jean-Marc Eric et al. A Structural Study of the Homogeneity Domain of LaNi5. In: Journal of solid state chemistry, 2002, vol. 166, n° 1, p. 1–6. doi: 10.1006/jssc.2001.9499

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Article (Published version)

Identifiers

Additional URL for this publication

http://linkinghub.elsevier.com/retrieve/pii/S002245960199499X

Journal ISSN

0022-4596
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08/04/2014 17:08:00

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08/04/2014 17:08:00

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