Thermodynamic Changes in Pd(Pt, Rh) Solid Solutions due to ³He Formation During Tritium Storage

Palladium and its alloys have been extensively studied because of their faculty to store reversibly hydrogen isotopes. Here, aging effects on pressure-composition isotherms of Pd(PtRh) solid solutions are investigated for tritium storage up to 5 years. The main changes observed are the decrease of the plateau pressures and the shift of the and branches towards greater stoichiometries, as it was already observed for pure palladium. In this study, we show that aging effects are greater on palladium substituted by platinum and/or rhodium than for pure palladium. These observations can be correlated to different evolutions of the structural and micro-structural properties of the solid solutions.