Mo La_2O_3模拟阴极的高温XPS/AES研究 Ⅱ.激活过程中La的变化及对发射的影响  

High Temperature XPS/AES Investigation of Mo La_2O_3 Model CathodeⅡ. Changes of La During Activation Processes and Its Effects on Emission

作　　者：聂祚仁[1] 左铁镛[1] 周美玲[1] 王亦曼[1] 王金淑[1] 张久兴[1] 

机构地区：[1]北京工业大学材料科学与工程学院,北京100022

出　　处：《中国稀土学报》1999年第4期342-346,共5页Journal of the Chinese Society of Rare Earths

基　　金：国家重点基础研究专项基金!资助项目(G1998061316)

摘　　要：选用片状样品考察ＭｏＬａ２Ｏ３ 阴极激活过程， 侧重分析Ｌａ 的存在状态和变化对热发射的影响。对高温ＸＰＳ实验结果的分析证实， 激活过程Ｌａ 的化学价态发生了改变， 伴随大量晶格氧的分离，Ｌａ２Ｏ３变成了缺氧化合物ＬａＯｘ（ｘ＜３／２） ， 即形成了超额的金属Ｌａ； 修正的Ａｕｇｅｒ 参数等变化趋势与上述相符。ＬａＯｘ 具有较低的逸出功是由于氧缺位的存在， 氧缺位对电子发射起到积极影响。激活过程促使Ｌａ，Ｏ离子的价电子态密度增加， 配位不饱和的Ｌａ 离子外层６ ｓ 高能价电子易形成电子发射， 即这一变化过程对热电子发射具有积极作用。The changes of La in the Mo La 2O 3 model cathode specimens were systematically investigated with in situ XPS/AES analyses from room temperature to 1550 ℃. The results indicate that the valence of La changes during the activation processes. With the dissociation of lattice oxygen, La 2O 3 in the cathode is partly reduced to LaO x(x <3/2) lacking of oxygen. Conforming to the Auger parameter in XPS analysis, excess lanthanum is formed, which is the source of high energy electrons. And the lack of lattice oxygen has a favorable effect on emission as well as leading to lower work function of LaO x . The density of state of valence electron of La and O ions increase during activation processes. The 6s higher energy valence electrons of La ions with unsaturated coordination number is easy to emit. It is clear that the processes is beneficial to thermionic emission.

关 键 词：钼 氧化镧 热阴极 模拟 XPS AES 阴极激活 

分 类 号：O462.1[理学—电子物理学]