Electronic structure study of Ce1-xAxO2(A = Zr & Hf) nanoparticles: NEXAFS and EXAFS investigations

Title
Electronic structure study of Ce1-xAxO2(A = Zr & Hf) nanoparticles: NEXAFS and EXAFS investigations
Authors
Aditya SharmaMayora VarshneyHyun-Joon ShinYong Jun ParkMin-Gyu KimTae-Kyun Ha채근화Sanjeev Gautam
Keywords
nanoparticles; CeO2; NEXAFS; EXAFS
Issue Date
2014-10
Publisher
Physical chemistry chemical physics : PCCP
Citation
VOL 16, NO 37, 19909-19916
Abstract
Single phase nanoparticles (NPs) of CeO2, Ce0.5Zr0.5O2, Ce0.5Hf0.5O2 and Ce0.5Hf0.25Zr0.25O2 were successfully synthesized by co-precipitation method at constant pH and temperature. The X-ray diffraction results revealed that the additive atoms did not segregate to form secondary phases but led to grain size variation in the NPs. The 10 Dq values in the near edge X-ray absorption fine structure (NEXAFS) spectra at the O K-edge did not vary in the same way as the average grain size was changed for the doped CeO2 NPs. The deconvolution of Ce M5-edge and detailed analysis of O K pre-edge peak have shown the higher Ce+3/(Ce+3 + Ce+4) ratio in the Zr- and Hf-doped samples. The local atomic structure around the Ce, Zr and Hf atoms was investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy at Ce K-edge, Zr K-edge and Hf L3-edge, respectively, and the EXAFS data were fitted with the theoretical calculations. The 4f occupancy, Ce+3/(Ce+3 + Ce+4) ratio of Ce ions, coordination number of Ce and Ce–Ce/Ce–O bond distances were sensitive to the additive atoms but not explicitly changed according to the grain size variation in the NPs.
URI
http://pubs.kist.re.kr/handle/201004/48161
ISSN
14639076
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KIST Publication > Article
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