Evolution of thermodynamics in Pd-H(D) system by tritium aging

Experiments on investigating the thermodynamics properties of palladium hydride after aging as palladium tritide with different storage periods upto 6.5 years have been performed. By analyzing the experimental results, it is found that during the formation and the decomposition of palladium hydride the entropy changes maintain a linear relationship with the helium content in solid, whereas the enthalpy changes keep constant. The sum of interstitial sites in the host palladium matrix is expected to be affected by helium, resulting in the modification on the entropy changes.