Oxygen isotope exchange in proton-conducting oxides based on lanthanum scandates
| Autor: | A.V. Fetisov, Nikita A. Shevyrev, Andrei S. Farlenkov, A. V. Khodimchuk, Maxim V. Ananyev, Anna Yu. Stroeva |
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| Rok vydání: | 2019 |
| Předmět: |
Strontium
Materials science Renewable Energy Sustainability and the Environment Reducing atmosphere Diffusion Oxide Analytical chemistry Energy Engineering and Power Technology chemistry.chemical_element 02 engineering and technology Atmospheric temperature range 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Oxygen Isotopes of oxygen 0104 chemical sciences chemistry.chemical_compound Fuel Technology chemistry Lanthanum 0210 nano-technology |
| Zdroj: | International Journal of Hydrogen Energy. 44:26577-26588 |
| ISSN: | 0360-3199 |
| Popis: | A method of the oxygen isotope exchange with equilibration of the gas phase was used in order to obtain the temperature dependences of the oxygen surface exchange and diffusion coefficients of the proton-conducting oxides La1–xSrxScO3–δ (x = 0; 0.04; 0.09) in the temperature range of 600–900 °C and oxygen pressure of 1.01 kPa. The diffusion and oxygen surface exchange coefficients increase with the strontium content in oxides. The rates of the individual stages of the oxygen exchange process on the surface of the oxides were determined. The oxygen incorporation was revealed to be rate-determining for the undoped LaScO3 oxide. However, for the strontium-doped oxides La1–xSrxScO3–δ (x = 0.04; 0.09), the difference between the rates of oxygen dissociative adsorption and oxygen incorporation decreases with increasing the strontium concentration, in a way that for the La0.91Sr0.09ScO3−δ oxide these stages become competing. The possible reasons for these differences in oxygen surface exchange kinetics were analyzed in this paper. Using the obtained oxygen diffusion coefficients, the oxygen-ionic conductivities in accordance with the Nernst-Einstein equation, and the contributions of the oxygen-ion and proton components of the total conductivity of the La1–xSrxScO3–δ (x = 0.04; 0.09) oxides in the wet reducing atmosphere (pH2O = 2.35 kPa, pO2 = 10−15 Pa) were calculated. The proton transference numbers were found to be close to unit at the wet reducing atmospheres in the temperature range of 500–600°С. |
| Databáze: | OpenAIRE |
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