Hydrogen absorption behaviour in nanometer sized palladium samples stabilised in soft and hard matrix

The reduction in the length scale of materials to the nanometer range brings about fundamental changes that lead to novel and unusual phenomena, very different from their coarse-grained counterparts. These differences are not only due to the different physical properties of the small-size system but it is also affected by the type of the stabiliser used on these materials. In situ X-ray diffraction (XRD) investigations of the hydrogen absorption behaviour in different nanometer sized palladium samples were performed during loading and unloading. Pressure-lattice parameter isotherms were constructed for three different samples: surfactant stabilised clusters, and two types of polymer stabilised samples (clusters and closed clusters layers sample). The pressure-lattice parameter isotherms for the samples show a narrowed lattice parameter miscibility gap. The closed clusters layers sample shows the smallest lattice parameter expansion values. The effect of the samples morphology on the lattice expansion will be discussed. It will be shown that not only the sample sizes affect the expansion but also the cluster surrounding plays an important rule. (c) 2005 Elsevier B.V. All rights reserved.