氧化物颗粒尺寸对Mo-La_2O_3阴极电子发射及真空电弧特性的影响(英文)  

Effect of Oxide Particle Size on Electron Emission and Vacuum Arc Characteristic of Mo-La_2O_3 Cathode

作　　者：郑雪萍[1] 刘丽丽[1] 张怀龙[1] 李文静[1] 王新刚[1] 王茂林[2] 丁秉钧[2] 

机构地区：[1]长安大学,陕西西安710061 [2]西安交通大学,陕西西安710049

出　　处：《稀有金属材料与工程》2015年第9期2114-2119,共6页Rare Metal Materials and Engineering

基　　金：National Natural Science Foundation of China(51177006);Fundamental Research Funds for the Central Universities(CHD2012ZD010)

摘　　要：采用高能球磨及热压烧结工艺制备了Mo-4%（质量分数,下同）La2O3纳米复合的阴极材料,其中La2O3的颗粒尺寸小于100 nm;作为比较,商业W-4%Th O2阴极材料中的Th O2颗粒尺寸为1~2μm。Mo-La2O3纳米阴极材料的平均真空起始电场强度为2.97×107V/m,比商业W-Th O2阴极材料低62.7%。纳米复合的Mo-La2O3阴极材料具有优异的电子发射性能,其电子发射点的分布面积和密度明显大于商业W-Th O2阴极材料。氧化物的颗粒尺寸对于阴极材料的电子发射性能以及真空电弧特性有显著的影响。随着La2O3颗粒尺寸的减小,Mo-La2O3阴极材料的电子发射性能提高。当La2O3的颗粒尺寸减小到小于100 nm时,Mo-La2O3阴极材料的电子发射面积和能力显著增加。纳米复合Mo-La2O3阴极材料电子发射性能的增强归因于在相界面上形成了高的内电场和空间电荷区。A nanocomposite Mo-4wt% La2O3 cathode was prepared by a high-energy ball-milling and hot pressing technique. The sizes of lanthana particles in the nanocomposite Mo-La2O3 cathode are less than 100 nm; in contrast, the sizes of thoria particles are about 1~2 μm in a commercial W-4wt% Th O2 cathode. The average vacuum arc-starting field intensity of the nanocomposite Mo-La2O3 cathode is 2.97×107 V/m, which is 62.7% lower than that of the commercial W-Th O2. The nanocomposite Mo-La2O3 cathode exhibits superior electron emission performances, and its distribution area and thickness of electron emission spots are remarkably larger, as compared to those of the commercial W-Th O2 cathode. The size of oxide particles has a great effect on the electron emission performances and vacuum arc characteristics of cathode. The electron emission performance of Mo-La2O3 cathode will be improved with decreasing of the lanthana particles size. When La2O3 particle size decreases to less than 100 nm, the electron emission area and ability of the Mo-La2O3 cathode significantly increase. The much enhanced electron emission performance of the nanocomposite Mo-La2O3 cathode is attributed to the formation of a higher inter electric field and space-charge regions at the interphase boundaries between Mo and La2O3 phases.

关 键 词：纳米复合 阴极 电子发射 真空电弧 

分 类 号：O646.541[理学—物理化学]