Mo-La_2O_3模拟阴极的高温XPS/AES研究 Ⅰ. 表面氧状态及其性质

High Temperature XPS/AES Investigation of MoLa2O3 Cathode . Species and Properties of Oxygen on Surface

对稀土氧化物体系Ｌａ２Ｏ３中Ｏ１ｓ的超高温原位ＸＰＳ进行研究，着重讨论了ＭｏＬａ２Ｏ３阴极激活过程中温度变化导致表面氧状态改变的过程，并初步分析其对电子发射性能的影响。高温１３００℃以上，存在两类不同氧种的氧，低结合能端（Ｅｂ＝５３０００ｅＶ）的氧是表面晶格氧，高结合能端（Ｅｂ＝５３２００ｅＶ）的氧为吸附氧；大量的高温吸附氧应是Ｌａ２Ｏ３中晶格氧分离造成。

The acitivation processes of MoLa2O3 model cathode specimens were systematically investigated with insitu high temperature XPS/AES analyses. The oxygen species produced during the processes were characterized at different temperature. The results show that there exist two kinds of oxygen ions after activation(above 1300 ), the surface lattice oxygen with lower binding energy(Eb=53000 eV) and the adsorbed oxygen with higher binding energy(Eb=53200 eV) which should be dissociated from the lattice oxygen of La2O3. It may be concluded that La2O3 is partly reduced to LaOx(x<3/2) with the dissociation of lattice oxygen. And the oxygen may play a favorable or unfavorable role to emission depending upon its relative quantity and relative position in the surface adsorption.