Valence state of europium and samarium in Ln2Hf2O7 (Ln = Eu, Sm) based oxygen ion conductors
| Autor: | Alexander N. Shchegolikhin, I. V. Kolbanev, E. Yu. Konysheva, Sergei A. Chernyak, A. V. Shlyakhtina, Nikolay V. Lyskov |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
Valence (chemistry) Process Chemistry and Technology Oxide Pyrochlore chemistry.chemical_element Conductivity engineering.material Oxygen Surfaces Coatings and Films Electronic Optical and Magnetic Materials Ion Samarium chemistry.chemical_compound chemistry Materials Chemistry Ceramics and Composites engineering Physical chemistry Europium |
| Zdroj: | Ceramics International. 47:26898-26906 |
| ISSN: | 0272-8842 |
| DOI: | 10.1016/j.ceramint.2021.06.099 |
| Popis: | Ln2(Hf2-xLnx)O7-x/2 (Ln = Sm, Eu; x = 0.1) pyrochlores have been prepared via mechanical activation of oxide mixtures, followed by heat treatment for 4h at 1450 and 1600 °C, respectively. According to the ESR data, the Eu cations on the Hf site in the Hf1-xEuxO6 octahedra in pyrochlore Eu2(Hf2-xEux)O7-x/2 (x = 0.1) are most readily oxidized and reduced. Oxidation at 840 °C for 24h in air reduces the total conductivity of the Ln2(Hf2-xLnx)O7-x/2 (Ln = Sm, Eu; x = 0.1) by a factor of 2.5–6, due to the decrease in the concentrations of oxygen vacancies and Ln2+ ions as a result of the oxidation. The anomalous low-frequency behavior of the permittivity of the Eu2(Hf2-xEux)O7-x/2 (x = 0.1) at ~800 °C can be understood in terms of the changes in the oxygen sublattice of the pyrochlore structure as a result of the oxidation of divalent europium and partial filling of oxygen vacancies at this temperature. |
| Databáze: | OpenAIRE |
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