Journalartikel

Jahr der Veröffentlichung: 2022

Seiten: 2737-2746

Zeitschrift: Journal of Physical Chemistry C

Bandnummer: 126

Heftnummer: 5

ISSN: 1932-7447

DOI Link: https://doi.org/10.1021/acs.jpcc.1c07942

Verlag: American Chemical Society

Abstract: 
The deconvolution of grain boundary and grain interior contributions to the total impedance of a polycrystalline material and their influence on its conductivity can be challenging, depending on the specific material. In this study, we present a microelectrode approach which enables the direct characterization of the electrochemical transport processes of individual grains with and without a grain boundary of microcrystalline oxide thin films by using electrochemical impedance spectroscopy. A combination of photolithography and electron-beam lithography was used to prepare welldefined microelectrodes onto a ceria thin film sintered at 1500 degrees C for 8 h to contact individual grains with and without a grain boundary. Impedance data was collected in the temperature range between 613 and 773 K and in an oxygen partial pressure range between 0.2 and 10(-5) bar. The conductivity of single grains increases with increasing oxygen partial pressure accompanied by a decrease of the activation energy from 1.32 to 0.93 eV. In contrast, the conductivity of grains with a grain boundary remains constant in the oxygen partial pressure range investigated. These differences are analyzed quantitatively in terms of the defect chemistry of the grain interior and the near grain boundary region, which differs due to the segregation of impurities at the grain boundaries. The results demonstrate that locally resolved measurements of the impedance of microcrystalline samples are a powerful tool to determine the transport characteristics of individual grains and grain boundaries as well as the equilibrium constants of the underlying defect chemical reactions.

Harvard-Zitierstil: Zahnow, J., Bastianello, M., Janek, J. and Elm, M. (2022) Defect Chemistry of Individual Grains with and without Grain Boundaries of Al-Doped Ceria Determined Using Well-Defined Microelectrodes, Journal of Physical Chemistry C, 126(5), pp. 2737-2746. https://doi.org/10.1021/acs.jpcc.1c07942

APA-Zitierstil: Zahnow, J., Bastianello, M., Janek, J., & Elm, M. (2022). Defect Chemistry of Individual Grains with and without Grain Boundaries of Al-Doped Ceria Determined Using Well-Defined Microelectrodes. Journal of Physical Chemistry C. 126(5), 2737-2746. https://doi.org/10.1021/acs.jpcc.1c07942