Abstract:The carbonized structures of Mo-La₂O₃ cathode specimens have been investigated by means of FESEM and XRD, respectively. The substructure of carbonized layer in the Mo-La₂O₃ cathode has been found for the first time. The results showed that the carbonized layer with uniform Mo₂C was helpful to emission, while the demixing carbonized layer with a compact MoC outside layer was harmful to emission. The uniform Mo₂C layer consists of coarse particles with lots of grain boundary crevices as well as holes arranging perpendicular to the wire axle and up to surface, which was beneficial to the migration of activated rare-earth in activation and operating.

Key words: microstructure; cathodes; Mo-La₂O₃; carbonization; emission