Electronic structure of nanoporous ceria from x-ray absorption spectroscopy and atomic multiplet calculations

Kucheyev, S. O.; Clapsaddle, Brady J.; Wang, Y. M.; Buuren, T. van; Hamza, A. V.

doi:10.1103/physrevb.76.235420

Cited by 37 publications

(51 citation statements)

References 32 publications

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“…Eventually an 88% Ce(III) could be obtained, but at a temperature as high as 720°C (T-11). This result agrees with XANES measurements carried out on 5 nm Ce 0.4 Zr 0.6 O 2 in the reducing atmosphere of forming gas at 800°C, where 70% Ce(III) was found (25); XANES on some as-prepared ceria aerogel also gave 90% Ce(III) (22).…”

Section: Ecs Transactions 25 (2) 1573-1582 (2009)supporting

confidence: 90%

Redox Properties of Ordered Macroporous Ce-Zr Mixed Oxides

Tonti¹,

Torralvo

Enciso

et al. 2009

ECS Trans.

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In this contribution finely textured three-dimensionally ordered macroporous (3DOM) mixed oxides of composition Zr 0.6 Ce 0.4 O 2 were prepared by the inverse opal technique. By using thermal analysis and photoelectron spectroscopy the oxygen storage and the redox response to different environments has been investigated. Multiple high temperature oxidation-reduction cycles decrease the initial high sensitivity of the surface oxidation state of Ce to the environment. This has been ascribed to the development of Ce(III) phases. Finally, we present a simple analysis of XPS data that allow the detection of surface inhomogeneities on Ce-containing oxides. We show that phase segregation can produce chemically heterogeneous surfaces.

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Section: Ecs Transactions 25 (2) 1573-1582 (2009)supporting

confidence: 90%

Redox Properties of Ordered Macroporous Ce-Zr Mixed Oxides

Tonti¹,

Torralvo

Enciso

et al. 2009

ECS Trans.

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“…34 We measured the Ce 3d spectra with fast scans before and after 2 h under irradiation, and the changes were minimal. 28 It is evident that the system was aged by a high temperature treatment and/or exposure to a strong reductive or oxidative atmosphere as in other reported cases. However, the values we measured are not exceptional in nanoparticulate ceria-zirconia: 70% Ce͑III͒ was found by X-ray absorption near-edge structure ͑XANES͒ measurements carried out on 5 nm Ce 0.4 Zr 0.6 O 2 particles in the reducing atmosphere of forming gas at 1000°C; 35 XANES even gave 90% Ce͑III͒ on some as-prepared ceria aerogels.…”

Section: Xps: Oxidation/reduction Behavior-mentioning

confidence: 72%

Redox Properties of Ordered Macroporous Ce–Zr Mixed Oxides

Tonti

Martínez

Torralvo³

et al. 2010

J. Electrochem. Soc.

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Chlorine-free, finely textured three-dimensionally ordered macroporous mixed oxides of nominal composition Zr 0.6 Ce 0.4 O 2 were prepared by the opal template technique. Electron microscopy showed a well-defined porosity that can be controlled with the infiltration process. By using thermal analysis and X-ray photoelectron spectroscopy ͑XPS͒, the oxygen storage and the redox response to different environments have been investigated. Multiple high temperature oxidation-reduction cycles decrease the initial high sensitivity of the surface oxidation state of Ce to the environment ͑aging processes͒. This has been ascribed to the development of Ce͑III͒-rich phases. Analysis of X-ray diffraction, energy-dispersive X-ray spectroscopy, and photoemission data indicated the coexistence of a Zr-rich and a Ce-rich phase. In XPS, we observe binding energy shifts in consequence of the redox treatments and explain them as shifts of the Fermi level linked to variations in the Ce oxidation state.

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“…For all XANES and XEOL measurements, multiple sample spots were tested to verify homogeneity of the samples. 18 The TEY and FLY results show the following: First, there is an evidence of oxidation of Ce on the surface ͑i.e., from Ce 3+ to Ce 4+ ͒ as indicated by more intense Ce 4+ feature in the surface-sensitive TEY for both Ba 1.90 Ce 0.05 Na 0.05 Ca͑BO 3 ͒ 2 and Ba 1.60 Ce 0.20 Na 0.20 Ca͑BO 3 ͒ 2 . Luminescence peaks are located at 409 and 498 nm with a shoulder at 388 nm.…”

Section: Methodsmentioning

confidence: 99%

“…14 All signals were normalized by incoming photon flux ͑I 0 ͒, which was measured using a gold mesh detector. 18 In the TEY plot of both Ba 1.90 Ce 0.05 Na 0.05 Ca͑BO 3 ͒ 2 and Ba 1.60 Ce 0.20 Na 0.20 Ca͑BO 3 ͒ 2 , multiplet effects are observed at 882, 883.2, and 884.5 eV, which are due to 3d 5/2 → 4f transition, and at 899.1, 900.3, and 902.1 eV, which are due to 3d 3/2 → 4f transition. Figure 2 shows XEOL spectra across Ce M 4,5 -edge of Ba 1.90 Ce 0.05 Na 0.05 Ca͑BO 3 ͒ 2 and Ba 1.60 Ce 0.20 Na 0.20 Ca͑BO 3 ͒ 2 .…”

Section: Methodsmentioning

confidence: 99%

X-ray absorption and luminescence studies of Ba2Ca(BO3)2: Ce3+/Na+ phosphors

Yiu

Liang

et al. 2010

The Journal of Chemical Physics

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X-ray excited optical luminescence (XEOL) spectroscopy has been used to investigate the optical emission properties of Ce(3+) activated Ba(2)Ca(BO(3))(2) with a charge-compensating Na(+) and the results are compared with the optical emission properties from UV excitation. Further, x-ray absorption near-edge structure (XANES) has been employed to study the chemical environment and energy transfer efficiency to optical emission upon x-ray excitation. XEOL results agree well with optical emission with UV excitation. XANES results across various absorption edges show that while the chemical environment of host materials does not change significantly with doping, luminescence yield decreases significantly at absorption edges due to an abrupt change in the de-excitation mechanism.

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Electronic structure of nanoporous ceria from x-ray absorption spectroscopy and atomic multiplet calculations

Cited by 37 publications

References 32 publications

Redox Properties of Ordered Macroporous Ce-Zr Mixed Oxides

Redox Properties of Ordered Macroporous Ce-Zr Mixed Oxides

Redox Properties of Ordered Macroporous Ce–Zr Mixed Oxides

X-ray absorption and luminescence studies of Ba2Ca(BO3)2: Ce3+/Na+ phosphors

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