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Research Letters in Physical Chemistry
Volume 2007 (2007), Article ID 96251, 5 pages
http://dx.doi.org/10.1155/2007/96251
Research Letter

Fourier-Domain Analysis of Hydriding Kinetics Using Pneumato-Chemical Impedance Spectroscopy

1Institut de Chimie Moléculaire et des Matériaux, CNRS UMR 8182, Université Paris-Sud 11, 15 rue Georges Clémenceau, Orsay Cedex 91405, France
2Compagnie Européenne des Technologies de l'Hydrogène (CETH), Innov' Valley Entreprise, Route de Nozay, Marcoussis Cedex 91461, France

Received 10 July 2007; Accepted 12 September 2007

Academic Editor: Claudio Fontanesi

Copyright © 2007 P. Millet et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Analysis of phase transformation processes observed in hydrogen absorbing materials (pure metals, alloys, or compounds) is still a matter of active research. Using pneumato-chemical impedance spectroscopy (PIS), it is now possible to analyze the mechanism of hydriding reactions induced by the gas phase. Experimental impedance diagrams, measured on activated LaNi5 in single- and two-phase domains, are reported in this paper. It is shown that their shape is mostly affected by the slope of the isotherm at the measurement point. By considering the details of the multistep reaction paths involved in the hydriding reaction, model impedance equations have been derived for single- and two-phase domains, and fitted to experimental impedance diagrams. The possibility of separately measuring surface and phase transformation resistances, hydrogen diffusion coefficient, and hydrogen solubility in each composition domain is discussed.