Hydration-induced chemical expansion of BaCa(1+y)/3Nb(2−y)/3O3−δ∙xH2O (BCN) and other proton-conducting perovskite oxides
| Autor: | Andrey Yu. Zuev, Dmitry S. Tsvetkov, Dmitry Malyshkin, Anton L. Sednev-Lugovets, Vladimir V. Sereda, I.L. Ivanov |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Ionic radius Proton chemistry.chemical_element Thermodynamics 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Kinetic energy 01 natural sciences Oxygen Thermal expansion 0104 chemical sciences Metal chemistry visual_art visual_art.visual_art_medium General Materials Science Density functional theory 0210 nano-technology Perovskite (structure) |
| Zdroj: | Solid State Ionics. 358:115516 |
| ISSN: | 0167-2738 |
| DOI: | 10.1016/j.ssi.2020.115516 |
| Popis: | Thermal expansion and chemical strain caused by water uptake were measured for BaCa(1+y)/3Nb(2−y)/3O3−δ∙xH2O (BCN) perovskite-type oxides by dilatometric and X-ray diffraction methods. To describe the total and chemical expansion, we proposed a simple geometric chemical strain model based on the relative change in ionic radii upon hydration. The model calculations agree well with the experimental data for BCN oxides, for which the values of the linear chemical expansion coefficient, β, were found to be around 0.038 per mole of water-filled oxygen vacancies. Next, the model was applied to different perovskite-type proton-conducting oxides with existing literature data on chemical expansion. For example, the values of β, estimated using the model, are around 0.036 and 0.031 for BaZr1−yMyO3−δ and BaCe1−yMyO3−δ, respectively (M = rare-earth metal, Y or Sc). These values are close to those obtained by others using either density functional theory (DFT) calculations or direct experimental measurements, especially given the rather large scatter in the data reported in the literature. The latter is most probably related to the kinetic limitations since, unlike the most oxygen exchange phenomena, humidification of oxides happens at lower temperatures where the slow kinetics of water uptake plays an important role. |
| Databáze: | OpenAIRE |
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