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Analysis of defect chemistry and microstructural effects of non-stoichiometric ceria by the high-temperature microwave cavity perturbation method

Title data

Steiner, Carsten ; Hagen, Gunter ; Kogut, Iurii ; Fritze, Holger ; Moos, Ralf:
Analysis of defect chemistry and microstructural effects of non-stoichiometric ceria by the high-temperature microwave cavity perturbation method.
In: Journal of the European Ceramic Society. Vol. 42 (2022) Issue 2 . - pp. 499-511.
ISSN 0955-2219
DOI: https://doi.org/10.1016/j.jeurceramsoc.2021.08.053

Official URL: Volltext

Project information

Project title:
Project's official titleProject's id
In-situ-Verfahren zur Bestimmung hoher Sauerstoffdefizite in Cer-Zirkon-Mischoxiden für den Einsatz in der AbgasnachbehandlungMO 1060/29-1

Project financing: Deutsche Forschungsgemeinschaft

Abstract in another language

The defect chemistry of ceria has been studied using a microwave resonator. The dielectric properties of powder samples were investigated up to 600 °C and at different oxygen partial pressures pO2 (10^-26 – 0.2 bar) and evaluated using the microwave cavity perturbation theory. For the ceria powder, an activation of the oxygen incorporation and release kinetics was observed from 480 °C onwards. The data suggest that the increased losses in non-stoichiometric ceria originate from the small polaron hopping mechanism, as known from literature. In addition, an increase in material polarization due to the formation of oxygen vacancies was experimentally observed. A comparison with sintered, coarse-grained samples of the same material and with literature data also demonstrated the importance of the microstructure for the defect chemistry of ceria. For the powder (ca. 80 nm grain size), significantly higher electronic conductivities (assumedly due to the higher concentration of small polarons) and lower activation energies were detected at 600 °C. On the other hand, lower conductivities, controlled by the concentration of acceptor cations in the material were reported for the sintered samples (1.1 μm) at this temperature. The findings are well in-line with existing defect chemical models of ceria. This study presents an analysis of the microwave behavior of ceria and provides insights into intrinsic and extrinsic mechanisms of oxygen exchange in ceria. The findings also contribute to a better understanding of microwave-based state diagnosis of three-way catalysts in automotive applications.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Functional Materials > Chair Functional Materials - Univ.-Prof. Dr.-Ing. Ralf Moos
Profile Fields > Advanced Fields > Advanced Materials
Research Institutions > Research Centres > Bayreuth Center for Material Science and Engineering - BayMAT
Research Institutions > Research Units > BERC - Bayreuth Engine Research Center
Result of work at the UBT: Yes
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 23 Nov 2021 08:54
Last Modified: 23 Nov 2021 08:54
URI: https://eref.uni-bayreuth.de/id/eprint/67965