Abstract
Recent experimental results of the dependence on oxygen partial pressure, P(O2), of the small polarons concentration in the monomolecular surface layer of doped ceria, are interpreted theoretically. Two different, experimental conditions are examined. First, the highly reduced surface of Sm0.2Ce0.8O1.9 – δ (SDC) is treated and the \({{[{\text{C}}{{{\text{e}}}^{{3 + }}}]}_{{\text{s}}}}{-}P({{{\text{O}}}_{2}})\) relations are evaluated. The experimental data are explained by a metallic surface layer, approximately neutral, i.e. with negligible transfer of charge to the bulk. The surface is metallic as the outer electrons on Ce3+ ions, which are small polarons when under low concentration, lose their localization under high concentration. Second, the surface of Pr0.1Ce0.9O2 – δ (PCO) is examined. The experimental data of \({{[{{\Pr }^{{3 + }}}]}_{{\text{s}}}}{-}P({{{\text{O}}}_{2}})\) relations are explained by a semiconducting, negatively charged, monomolecular surface layer forming a double layer with a positive bulk. In both SDC and PCO the surface defect concentration dependence on P(O2) is different from that of the bulk.
REFERENCES
Oswald, S., Encyclopedia of Analytical Chemistry, John Wiley & Sons, March, 2013.
Chueh, W.C., McDaniel, A.H., Grass, M.E., Hao, Y., Jabeen, N., Liu, Z., Haile, S.M., McCarty, K.F., Bluhm, H., and El Gabaly, F., Highly enhanced concentration and stability of reactive Ce3+ on doped CeO2 surface revealed in Operando, Chem. Mater., 2012, vol. 24, p. 1876.
Lu, Q., Vardar, G., Jansen, M., Bishop, S.R., Waluyo, I., Tuller, H.L., and Yildiz, B., Surface defect chemistry and electronic structure of Pr0.1Ce0.9 O2 − δ revealed in Operando, Chem. Mater., 2018, vol. 30, p. 2600.
Devreese, J.T. and Peeters, F.M., Electron-phonon interaction in two-dimensional systems: polaron effects and screening, in The Physics of the Two-Dimensional Electron Gas, Devreese, J.T. and Peeters, F.M., Eds., Springer, 1987, p. 131.
Riess, I., Analysis of point defect concentrations in highly reduced, monomolecular surface layer of doped ceria, Solid State Ionics, 2021, vol. 373, p. 115791.
Ricken, M., Nölting, J., and Riess, I., Specific heat and phase diagram of non stoichiometric ceria (CeO2 – δ), J. Solid State Chem., 1984, vol. 54, p. 89.
Stelzer, N., Nölting, J., and Riess, I., Phase diagram of nonstoichiometric 10 mol % Gd2O3 doped cerium oxide determined from specific heat measurements, J. Solid State Chem., 1995, vol. 117, p. 392.
Riess, I., Analysis of the unique dependence on oxygen pressure of Pr3+ concentration in the surface of Pr doped ceria, Solid State Ionics, 2022, vol. 380, p. 115899.
Chatzichristodoulou, C. and Hendriksen, P.V., Analysis of the unique dependence on oxygen pressure of Pr3+ concentration in the surface of Pr doped ceria, J. Electrochem. Soc., 2010, vol. 157, p. B481.
ACKNOWLEDGMENTS
This work was supported by the Technion V.P. for Research Fund, no. 2023320.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
The authors declare that they have no conflict of interest.
Additional information
Based on the materials of the 16th International Meeting “Fundamental Problems of Solid State Ionics”, Chernogolovka, June 27–July 7, 2022.
Rights and permissions
About this article
Cite this article
Ilan Riess Analysis of Experimental Results of Defect Concentraions in the Surface Layer of Acceptor Doped Ceria. Russ J Electrochem 59, 169–172 (2023). https://doi.org/10.1134/S1023193523030114
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S1023193523030114