Abstract:Y₂O₃-doped Mo secondary emitters were prepared by liquid-liquid doping and solid-solid doping, respectively. The back-scattered scanning observation result indicates that the emitter prepared by liquid-liquid doping has fine microstructure whereas that prepared by solid-solid doping has large grain size. Y₂O₃-doped Mo emitter with small grain size prepared by liquid-liquid doping exhibits high emission property, i.e., the secondary electron yield can get to 5.24, about 1.7 times that prepared by solid-solid doping. Moreover, Y₂O₃-doped Mo emitter exhibits the best emission performance among La₂O₃-doped Mo, Y₂O₃-doped Mo, Gd₂O₃-doped Mo and Ce₂O₃-doped Mo emitters due to the largest penetration depth of primary electrons and escape depth of secondary electrons in this emitter. The secondary emission of the emitter with small grain size can be explained by reflection emission model and transmission emission model, whereas only transmission emission exists in the emitter with large grain size.

Key words: Y₂O₃-doped Mo; powder metallurgy; emission property; microstructure