Waldow, Stephan ; Wardenga, Hans ; Beschnitt, Stefan ; Klein, Andreas ; De Souza, Roger A. (2019)
The Concentration and Diffusivity of Oxygen Interstitials in Niobia-Doped Ceria.
In: The Journal of Physical Chemistry C, 123 (11)
doi: 10.1021/acs.jpcc.8b10613
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
We studied the behaviour of oxygen interstitials in donor-doped ceria using equilibrium conductivity measurements, conductivity relaxation experiments and (18O2 / 16O2) isotope exchange experiments. Equilibrium conductivities and conductivity relaxation experiments were performed in the oxygen activity range 10-6 ≤ aO2 ≤ 10-1 at temperatures of 923 K, 973 K and 1023 K. Oxygen isotope exchanges were carried out at 673 ≤ T / K ≤ 1073 at an oxygen activity of aO2 = 0.2, and oxygen isotope profiles in the solid were obtained by Secondary Ion Mass Spectrometry (SIMS). Analysis of the measured equilibrium conductivities with a defect-chemical model yielded the incorporation enthalpy and entropy of oxygen interstitials. Values of the chemical diffusion coefficient of oxygen (from relaxation experiments) and of the tracer diffusion coefficient of oxygen (from isotope exchange experiments) were converted into diffusion coefficients of oxygen interstitials using the defect-chemical model. Based on these data, the activation enthalpy of oxygen-interstitial migration in Ce0.99Nb0.01O2+δ was found to be (1.28 ± 0.13) eV. Strong enrichment of Si, Ca and Al at the surfaces of the ceramic samples prevented the determination of surface exchange coefficients that refer to donor-doped ceria.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2019 |
| Autor(en): | Waldow, Stephan ; Wardenga, Hans ; Beschnitt, Stefan ; Klein, Andreas ; De Souza, Roger A. |
| Art des Eintrags: | Bibliographie |
| Titel: | The Concentration and Diffusivity of Oxygen Interstitials in Niobia-Doped Ceria |
| Sprache: | Englisch |
| Publikationsjahr: | 20 Februar 2019 |
| Verlag: | ACS Publications |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | The Journal of Physical Chemistry C |
| Jahrgang/Volume einer Zeitschrift: | 123 |
| (Heft-)Nummer: | 11 |
| DOI: | 10.1021/acs.jpcc.8b10613 |
| URL / URN: | https://doi.org/10.1021/acs.jpcc.8b10613 |
| Kurzbeschreibung (Abstract): | We studied the behaviour of oxygen interstitials in donor-doped ceria using equilibrium conductivity measurements, conductivity relaxation experiments and (18O2 / 16O2) isotope exchange experiments. Equilibrium conductivities and conductivity relaxation experiments were performed in the oxygen activity range 10-6 ≤ aO2 ≤ 10-1 at temperatures of 923 K, 973 K and 1023 K. Oxygen isotope exchanges were carried out at 673 ≤ T / K ≤ 1073 at an oxygen activity of aO2 = 0.2, and oxygen isotope profiles in the solid were obtained by Secondary Ion Mass Spectrometry (SIMS). Analysis of the measured equilibrium conductivities with a defect-chemical model yielded the incorporation enthalpy and entropy of oxygen interstitials. Values of the chemical diffusion coefficient of oxygen (from relaxation experiments) and of the tracer diffusion coefficient of oxygen (from isotope exchange experiments) were converted into diffusion coefficients of oxygen interstitials using the defect-chemical model. Based on these data, the activation enthalpy of oxygen-interstitial migration in Ce0.99Nb0.01O2+δ was found to be (1.28 ± 0.13) eV. Strong enrichment of Si, Ca and Al at the surfaces of the ceramic samples prevented the determination of surface exchange coefficients that refer to donor-doped ceria. |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Elektronenstruktur von Materialien |
| Hinterlegungsdatum: | 01 Mär 2019 07:26 |
| Letzte Änderung: | 08 Apr 2019 15:11 |
| PPN: | |
| Sponsoren: | The authors acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) from projects SO 499/7-1 and KL 1225/7-1. |
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