Effect of thermal treatment on the 4f-hopping conductivity of CeO2 exposed to CO(g) atmosphere
Abstract: The thermal treatment of CeO2 at 600 and 900 °C on the film response against CO is analyzed. A fluorite-type crystalline structure was observed, with the later presenting a well-defined morphology formed by the set of (1 0 0), (1 1 0) and (1 1 1) surfaces. The band-gap was 3.35 and 3.37 eV, for the 600 and 900 °C samples. We have proposed an equation based on the mass action law that shows the dependence of the carriers density as a function of the grain size, demonstrating that the area-volume relation can affect the number of charge carriers, which reflects in the pre-exponential A factor of conductivity. Reducing gases generate a greater number of carriers available for conduction, reflected on the A factor. When vacancies are annihilated by exposing to an oxygen atmosphere, the Ce (III) amount reduces. The activation energy and pre-factor A in air, vacuum and CO were calculated for correlating with the sample morphologies.
Author(s): Procópio, A. M. S.; Rocha, L. S. R.; Desimone, P. M.; Giulietti, G.; Aldao, C. M.; Longo, E.; Moura, F.; Ponce, M. A.
Materials Science and Engineering: B
Published: June 2023, Volume 292, 116403
DOI: https://doi.org/10.1016/j.mseb.2023.116403
CDMF
The CDMF, hosted at the Federal University of São Carlos (UFSCar), is one of the Research, Innovation and Dissemination Centers (RIDC) supported by the São Paulo State Research Support Foundation (Fapesp), and also receives investment from the National Council Scientific and Technological Development (CNPq), from the National Institute of Science and Technology of Materials in Nanotechnology (INCTMN).
