掺杂稀土氧化物的钼阴极次级发射性能的研究

Study on Secondary Emission Properties of the Molybdenum Cathode Doped with Ln2O3

为研制和开发一种理想的阴极材料,替代现有的应用于磁控管的Ba-W阴极和Th-W阴极,用粉末冶金方法制备了掺杂不同比例的一元、二元稀土氧化物的钼基体阴极材料,测试了各种材料的次级发射系数.结果表明,掺杂后的阴极材料的次级发射性能大大提高,掺杂复合稀土氧化物的次级发射体的发射性能优于掺杂单元稀土氧化物的次级发射体的发射性能.同时,应用扫描电镜（SEM）和俄歇电子能谱仪（AES）研究了稀土元素在钼烧结体断口和表面的分布.分析结果表明,稀土元素易于在晶界处偏聚,且稀土元素在试样表面的质量分数明显高于其在基体内部的质量分数.

In order to research and develop a kind of ideal cathode material so as to replace the existing Ba-W and Th-W cathodes used in magnetron, the powder metallurgy method was adopted to prepare the cathod material of substrate molybdenum doped with Ln2O3 in different proportion. The secondary emission coefficients of all the materials were also tested. The results show that the secondary emission properties of the doped cathode material are much higher than that of pure molybdenum cathode; The secondary emittor doped with composite rare-earth oxides is better than that with elementary rare-earth oxides in emission property. In addition, scanning electronic microscopic (SEM) and Auger electronic spectrum (AES) were employed to study the distribution of rare-earth elements at/ on the fracture and surface of molybdenum sinter. The analysed results show that rare-earth tends to gather at grain boundaries and the relevent concentration of rare-earth on the surface of sample is obviously higher than that in the interior of the material.