Effect of the substrate on the thermodynamic properties of PdHx films studied by hydrogenography

We investigated the influence of the substrate on the thermodynamic properties of metal hydride thin films by hydrogenography using PdHx as a model system. After appropriate hydrogen cycling, reproducible hydrogenation properties are found at the same equilibrium pressure for all substrates studied. Comparing these thin films with free-standing films-measured both by hydrogenography and by Sievert's method-we find a very similar behavior. Hence, thin films can be used to study the hydrogenation behavior of the corresponding bulk materials. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.