Local structure adaptations and oxide ionic conductivity in the Type III stability region of (1–x)Bi2O3∙xNb2O5
| Autor: | Chris D. Ling, Thomas Vogt, Julia Wind, Neeraj Sharma, Douglas A. Blom, Aleksey A. Yaremchenko, Vladislav V. Kharton |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Range (particle radiation)
Materials science 030206 - Solid State Chemistry [FoR] General Chemical Engineering Analytical chemistry Oxide 02 engineering and technology General Chemistry Conductivity 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Metal chemistry.chemical_compound chemistry visual_art Phase (matter) Scanning transmission electron microscopy Materials Chemistry visual_art.visual_art_medium Ionic conductivity 0210 nano-technology Stoichiometry |
| Popis: | Starting from a previously published stoichiometric model for the commensurate Type III phase in the (1–x)Bi2O3∙xNb2O5 system, Bi94Nb32O221 (x = 0.254), we have developed a crystal-chemical model of this phase across its solid-solution range 0.20 ≤ x ≤ 0.26. After using annular dark-field scanning transmission electron microscopy to identify the metal sites that support non-stoichiometry, we show that the maximum possible range of that non-stoichiometry is 0.198 ≤ x ≤ 0.262, perfectly consistent with the experimental result. Inter-site cation defects on these sites provide some local coordinative flexibility with respect to the surrounding oxygen sublattice, but not enough to create continuous fluorite-like channels like those found in the high-temperature incommensurate Type II phase. This explains the reduced oxide-ionic conductivity of Type III compared to Type II at all temperatures and compositions, regardless of which phase is thermody-namically stable under those conditions. The solid-solution model shows that oxygen disorder and vacancies are both re-duced as x increases, which also explains why Type III becomes relatively more stable, and why oxide ionic conductivity decreases, as x increases. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|