On the valence states of cerium in CeO2

Decreased electrochromism in Li-intercalated Ti oxide films containing La, Ce, and Pr

“…69,71 Photoabsorption spectra due to 4d→4 f transitions give a supporting picture. [72][73][74][75] The XPS and BIS data are well explained through the calculations by Koelling et al 76 showing a narrow 4 f band amidst a band gap of ϳ6 eV. However, this body of consistent results does not seem to lead to a complete picture of the electronic structure, and some detailed analyses of photoabsorption and photoemission spectra were interpreted 71,77-79 on the premise that the ground state of CeO 2 is strongly mixed valent between the 4 f 0 and 4 f 1 L configurations, and that the average 4 f electron number is ϳ0.5 ͑L denotes a hole in the valence band͒.…”

Mixed valency in cerium oxide crystallographic phases: Valence of different cerium sites by the bond valence method

“…30,31,32,33,34,35,36,37 In contrast to the 3d XPS and XANES data discussed above, the 4d-4f photoabsorption spectra of CeO 2 support the f 0 ground state configuration based on their close resemblance to La trihalide spectra which have no f electron while they differ considerably from the Ce trihalide spectra which have one f electron. 38,39 Also in favour of the f 0 ground state configuration are results from reflectance spectroscopy in the 4d-4f absorption region.…”

“…Application of resonant photoemission to the problem led to the conclusion that the ground state of CeO 2 is mixedvalent by some authors 41,42 while a pure f 0 configuration was claimed by others. 38,39,43 The spectrum investigated by the bremstrahlung isochromat spectroscopy (BIS) combined with XPS study shows empty localized 4f states in the band gap providing evidence in support of the pure f 0 configuration. 23,44 This conclusion was also supported by valence band XPS studies.…”

Photoemission study of Ce/Ta(110) and Ce/W(110) interfaces and the catalytic oxidation effect

“…The absorption spectrum, especially the fine-structure part, is very sensitive to the occupancy of the 4/ level. Fine structures taken from a-Ce [10], Ce02 [43], and…”

“…Figure 2.3: Ce 4d -> 4/ absorption spectra (after Refs, [10], [43], and [44]) and a-Ce, due to the small change in the 4/ occupancy in the phase transformation.…”