In situ X-ray diffraction analysis of the Pd-H system at high pressure

In the present work palladium thin foils have been hydrogenated at high pressure. In situ monochromatic X-ray diffraction performed under 5 GPa of hydrogen pressure has allowed to follow the formation of hydrogen-rich Pd-H phases as well as the presence of ordered superabundant vacancy phases. The occurrence of hydrogen-rich Pd-H phases as well as the presence of ordered superabundant-vacancy phase is discussed. Sme discrepancies with the early experiments of Fukai are observed. In particular, our results suggest the occurrence of a superstoichiometric defect hydride related to the γ′ phase. A structural model is proposed and needs to be confirmed by using neutron diffraction.