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

Cristina Artini, Sabrina Presto, Sara Massardo, Marcella Pani, Maria Maddalena Carnasciali and Massimo Viviani
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Cristina Artini: Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy
Sabrina Presto: 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
Sara Massardo: Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy
Marcella Pani: Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy
Maria Maddalena Carnasciali: Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy
Massimo Viviani: 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

Energies, 2019, vol. 12, issue 21, 1-11

Abstract: 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 (Ce 1− x Gd x O 2− 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 CeO 2 -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.

Keywords: solid oxide fuel cells (SOFCs); ionic conductivity; raman spectroscopy; powder x-ray diffraction; doped ceria (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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