A study on palladium-hydrogen interaction by positron annihilation technique

The behavior and interaction of hydrogen atoms with defects in hydrogen charged Pd electrodes were studied using the positron annihilation (PA) method. Lifetime results from PA measurements of the Pd electrodes indicated that hydrogen atoms could be trapped at dislocations and vacancies in the electrodes and that dislocations were slightly more preferred sites than vacancies. It was also inferred from R parameters that the formation of hydrides was accompanied by generation of mostly dislocations. Doppler broadening results from Pd electrodes also indicated that lattice defect sites where positrons were trapped first increased and then decreased, and this cycle was repeated as electrolysis continued. It can be inferred from PA measurements of the cold-rolled Pd and the isochronally annealed Pd hydride specimens that microvoid-type defects existed in the hydrogen-charged electrode specimen