金属铈表面氧化还原过程的原位拉曼光谱研究

In Situ Raman Spectroscopic of Cerium Surface Oxidation and Reduction Processes

采用显微拉曼光谱仪原位监测了金属铈表面的氧化和还原过程。2132和2239 cm-1处尖锐Ce3+电子散射峰的出现及462 cm-1处CeO2特征振动峰的消失表明,在高温、高真空条件下金属铈表层的CeO2已转变为Ce2O3。根据1503,1796和2113 cm-1处多个Ce3+电子散射峰及CeO2特征振动峰强度随时间的变化关系,可将金属Ce在空气中的氧化过程分为3个阶段,首先不同价态铈氧物层均快速增长,随后外层的CeO2陷入停顿,含Ce3+的铈氧物层继续增长,最后随着3603 cm-1处OH-的出现,CeO2再次快速增长。

The surface oxidation and reduction processes of cerium were monitored by in situ microscope Raman spectroscopy.A peak at 462 cm-1 attributed to the characteristic vibration of CeO2 disappeared and two sharp peaks at 2132 and 2239 cm-1 attributed to the electronic scattering of Ce3＋ were observed at high temperature and vacuum conditions.The results indicated that the surface oxide on cerium sample were transformed from CeO2 to Ce2O3.According to the changes of peak intensities at 1503,1796,2100 cm-1,also attributed to electronic scattering of Ce3＋ and the characteristic vibration peak of CeO2,the surface oxidation process of cerium in the air could be divided into three steps.First,all cerium oxide layers with different cerium valence increased quickly.Then,the outer CeO2 layer stopped growing,but those cerium oxide layers contained Ce3＋ continued growing.Finally,CeO2 layer increased quickly again with the appearance of OH-at 3603 cm-1.