Y2O3含量对Y-Gd-Hf-O直热式压制阴极发射性能的研究

Investigation of Influence of Y2O3 Contents for the Y-Gd-Hf-O Directly-Heated Pressed Cathode Thermionic Emission Properties

摘要:

为了提高Y-Gd-Hf-O压制式高温阴极的热发射性能，制备了Y2O3/HfO2摩尔比不同的S2O3掺杂Y-Gd-Hf-O直热式压制阴极。测试结果显示，当比值为5/2时，热发射能力最好，1500 ℃下发射电流为2.79 A/cm2。阴极支取直流发射电流密度1.0 A/cm2，在1500 ℃的工作温度下，已经稳定工作了1320 h，并在该温度下经过696 h的10 W连续电子轰击后，发射电流仍保持为初始值的86%，表现出良好的耐电子轰击能力。XPS结合深度刻蚀表明，发射活性层主要集中在距表面50 nm深度范围内。表层SEM、EDS分析表明，阴极经过激活、老炼，活性物质粒径变大，Y/Hf原子比低于初始值，且随着Y2O3含量的提高，阴极表层n型半导体Y2O3-x的含量相应地增加，对改善阴极表面的导电性、降低逸出功和提高阴极的热发射性能有促进作用

Abstract:

To improve the Y-Gd-Hf-O pressed cathode thermionic emission ability, Sc2O3 doped different molar ration of Y2O3/HfO2 pressed cathodes are prepared. The cathode with ratio of 5/2 demonstrates the best emission ability of 2.79 A/cm2 at 1500℃. The cathode has worked stably over 1320 h at 1500 ℃ with the load of 1 A/cm2 during the lifetime test, and the emission decrease to 86% of the initial one under 10 W, 696 h continuous bombardment at the same temperature, reflecting a good anti-electron bombardment ability. XPS depth profile results show the main active substances in work are concentrated in the depth range of 50 nm from the surface. After cathode being activated, the SEM and EDS results show the active materials diameter increase to an extent, and the surface n-type semiconductor contents increase with the Y2O3, which is favorable for enhancing the conductivity, improving thermionic emission, and lowering the work function.