Pd/H system in H2 plasmas -: art. no. 043304

The absorption of hydrogen by Pd wire samples has been studied at 299 K and in the H-2 pressure range from 18 to 1800 mbar under both tensile stress and tensile stress under cold H-2 plasma. Plasma is generated in a corona discharge regime by applying a dc high voltage between a Pd wire and a cylindrical counterelectrode. Positive and negative coronas have been performed. Three independent experimental quantities have been simultaneously measured: ratio x=n(H)/n(Pd), with n the number of atoms; ratio R/R-0, with R the four-probe resistance of the wire and R-0 the resistance when x=0; and ratio Deltal/l(0), with Deltal the length change of the wire and l(0) its length when x=0. From the thermodynamic analysis of data, the absorption standard chemical potential, Deltamu(abs)(0), and the excess chemical potential, Deltamu(exc), of hydrogen atoms in Pd have been obtained. At constant T, H-2 pressure, and tensile stress, the x value under cold plasma is always higher. (C) 2005 American Institute of Physics.