Aging effects on thermodynamics in palladium–tritium system during tritium storage

The absorption and desorption pressure–composition isotherms in a palladium–tritium system have been experimentally measured at 35, 50, 65 and 75∘C using the PVT method for tritium storage up to 3 years. Results show that the storage properties are remarkably well preserved during aging, and only small modifications of P–c   isotherms are observed: a decrease of plateau pressures and shifts of αα single phase regions toward greater stoichiometries. At a temperature in the range 35–75∘C, absorption transition enthalpies of aged palladium tritide is 30.1 kJ/mol, desorption transition enthalpies of the unaged is 34.6 kJ/mol and absorption–desorption transition entropy of the aged palladium tritide is less than the unaged. The hysteresis coefficient decreases with the temperature.