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Open AccessArticle

Transport Properties and High Temperature Raman Features of Heavily Gd-Doped Ceria

1
Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy
2
Institute of Condensed Matter Chemistry and Technologies for Energy, National Research Council, CNR-ICMATE, Via De Marini 6, 16149 Genova, Italy
3
Institute of Condensed Matter Chemistry and Technologies for Energy, National Research Council, CNR-ICMATE, c/o DICCA-UNIGE, Via all’Opera Pia 15, 16145 Genova, Italy
4
CNR-SPIN, Corso Perrone 24, 16152 Genova, Italy
5
INSTM, Genova Research Unit, Via Dodecaneso 31, 16146 Genova, Italy
*
Author to whom correspondence should be addressed.
Energies 2019, 12(21), 4148; https://doi.org/10.3390/en12214148
Received: 1 October 2019 / Revised: 22 October 2019 / Accepted: 29 October 2019 / Published: 30 October 2019
(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)
Transport and structural properties of heavily doped ceria can reveal subtle details of the interplay between conductivity and defects aggregation in this material, widely studied as solid electrolyte in solid oxide fuel cells. The ionic conductivity of heavily Gd-doped ceria samples (Ce1−xGdxO2−x/2 with x ranging between 0.31 and 0.49) was investigated by impedance spectroscopy in the 600–1000 K temperature range. A slope change was found in the Arrhenius plot at ~723 K for samples with x = 0.31 and 0.34, namely close to the compositional boundary of the CeO2-based solid solution. The described discontinuity, giving rise to two different activation energies, points at the existence of a threshold temperature, below which oxygen vacancies are blocked, and above which they become free to move through the lattice. This conclusion is well supported by Raman spectroscopy, due to the discontinuity revealed in the Raman shift trend versus temperature of the signal related to defects aggregates which hinder the vacancies movement. This evidence, observable in samples with x = 0.31 and 0.34 above ~750 K, accounts for a weakening of Gd–O bonds within blocking microdomains, which is compatible with the existence of a lower activation energy above the threshold temperature. View Full-Text
Keywords: solid oxide fuel cells (SOFCs); ionic conductivity; raman spectroscopy; powder x-ray diffraction; doped ceria solid oxide fuel cells (SOFCs); ionic conductivity; raman spectroscopy; powder x-ray diffraction; doped ceria
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MDPI and ACS Style

Artini, C.; Presto, S.; Massardo, S.; Pani, M.; Carnasciali, M.M.; Viviani, M. Transport Properties and High Temperature Raman Features of Heavily Gd-Doped Ceria. Energies 2019, 12, 4148.

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