A work model for barium dispenser cathodes with the surface covered by metal Os, Ir or Os 〈Ir〉 W alloy layer

According to the existing experimental data the Os (Ir) covered cathodes have a complex of submonoatomic layers of Ba and O on a substrate consisting of W and Os (Ir). Such a multicomponent surface structure is produced when the cathodes are subjected to an activation process. It is interesting to study the possibility of the creation of the active layers by the methods of direct deposition in this system. We have measured the work function and the adsorption energy of the layers of BaO on the metals W, Re, Os, Ir, the alloys of W and Os, containing 35%, 50%, 65% and 80% of Os, the 50% alloy of W with Ir and on the (111), (100), (112) and (110) of W. It was found that all Re, Os or Ir containing substrates covered with BaO have a lower work function and a higher adsorption energy than a W substrate. The high adsorption energy found for BaO on the alloys of W with Os or Ir are attributed to the unusually high work function of the alloys, that even exceed the work function of the metal Os.