金属Ce表面氧化物的真空稳定性

为探讨金属铈在超高真空条件下作为钚模拟材料的可行性，采用X射线光电子能谱（XPS）分析技术研究了超高真空条件下金属Ce表面氧化物在不同温度时的真空稳定性。实验结果表明，不同温度和超高真空条件下，金属Ce表面氧化物的真空稳定性各不相同。在室温、超高真空条件下没有观察到金属Ce表面氧化物发生变化；但在873 K、超高真空条件时，金属Ce表面氧化物发生还原反应，样品表面生成Ce₂O₃。根据热力学计算，推断了高温、超高真空条件下发生还原反应的过程，金属Ce表面氧化物的真空特性与金属Pu存在一定差异。

Stability of Surface Oxides on Cerium Metal

Cerium metal is considered as a surrogate of plutonium because of their similarities in physical and chemical properties for scientific research.In order to investigate the feasibility of cerium as a surrogate of plutonium under ultra-high vacuum condition(UHV),stabilities of surface oxides on cerium metal under UHV conditions were studied by the X-ray photoelectron spectroscopy(XPS).Cerium sample was stored in analysis chamber under UHV condition at room temperature for 19 d and 3 d,respectively.And then,the sample was heated to 673 K and 873 K in order to see any changes on the surface.The results show that the stabilities of surface oxides on cerium metal vary with temperature.At room temperature,there is no change observable on the surface from Ce3d XPS spectra after the storage of 19 d and 3 d respectively.And some deoxidization is found at 673 K and 873 K under UHV condition.Surface oxides on cerium sample transform from CeO2 to Ce2O3.The transformation is similar to that of plutonium,but the reacting condition for cerium is more rigid than that for plutonium.Attempts on deducing the process of deoxidization was carried out by thermo-dynamical calculations,and the mechanism may not be the same.So there are some difference in properties under UHV between surface oxides on cerium metal and those on plutonium.