Vibrational entropies of hydrogen in palladium-silver-hydrogen alloys by the isotopic solubility ratio method

The solubilities of hydrogen and deuterium in Pd−Ag alloys containing 10, 20, 30 and 40 wt. % Ag were measured at 125°C by the Sieverts' technique using Pd black as the transference catalyst. The results obtained were analysed in terms of the isotopic solubility ratio theory. In the Pd−10Ag−H, Pd−20Ag−H and Pd−30Ag−H alloy systems, there was no significant change in the partial vibrational entropy of hydrogen SH/V in the range of hydrogen contents H/M from 0·025 to 0·325, nor was there any marked difference between these systems. However in the Pd−40Ag−H system, SHV decreased markedly with increasing hydrogen concentration in the range of H/M from 0·050 to 0·150.