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利用溶胶-凝胶、氢气还原及热压工艺制备了纳米复合Mo-4La2O3(质量分数,%)阴极材料,其显微组织中La2O3粒径小于100nm,而常规Mo-4La2O3阴极中La2O3粒径为200～300nm。在真空击穿实验中发现La2O3粒径对于阴极电子发射性能有显著的影响,纳米复合阴极的电子发射能力远高于常规阴极的发射能力,其电子发射点遍布整个阴极表面,而常规阴极电子发射点只是集中在一小块区域。通过建立金属-半导体电子相互作用模型,计算并绘制了Mo及La2O3中电子隧穿几率随La2O3粒径变化的关系曲线,解释了纳米复合阴极电子发射能力强的原因。
The nano-composite cathode material of Mo-4La2O3 (mass fraction) was prepared by sol-gel, hydrogen reduction and hot pressing. The size of La2O3 in the microstructure was less than 100 nm, while the particle size of La2O3 in the conventional Mo-4La2O3 cathode was 200 ~ 300nm. La2O3 particle size was found to have a significant effect on the cathode electron emission performance in the vacuum breakdown experiment. The electron emission capability of the nanocomposite cathode is much higher than that of the conventional cathode, and its electron emission sites are distributed over the entire cathode surface. Conventional cathodic electron emission Points just focus on a small area. Through the establishment of the metal-semiconductor interaction model, the relationship between the electron tunneling probability and the particle size of La2O3 in Mo and La2O3 is calculated and plotted, and the reasons for the strong electron emission of the nanocomposite cathode are explained.