Solution of hydrogen in thin films of a palladium–silver alloy

Abstract

The absorption of hydrogen in evaporated Pd–Ag (5–7 atom % Ag) films with thicknesses of 360, 1150 and 2160 Å has been studied volumetrically from –40 °C to room temperature. Thermodynamic parameters in the range of the α-phase have been determined for the films and are compared with those for bulk alloys. It is found that the hydrogen solubilities in the films are larger than in the bulk alloys, and these tend to increase with decreasing film thickness. The absolute values of W_HH(the interaction energy of dissolved hydrogen) for the films are much smaller than those for the bulk alloys, and these values are found to increase with an increase in the film thickness. It is suggested that the solubility enhancement in the α-phase and the weakening of H–H interactions are mainly caused by stresses which are created during the deposition of the films.