Variable-temperature multinuclear solid-state NMR study of oxide ion dynamics in fluorite-type bismuth vanadate and phosphate solid electrolytes
| Autor: | Clare P. Grey, Ivana Radosavljevic Evans, Matthew T. Dunstan, Matthew L. Tate, David M. Halat |
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| Přispěvatelé: | Dunstan, MT [0000-0002-6319-4231], Halat, DM [0000-0002-0919-1689], Evans, IR [0000-0002-0325-7229], Grey, CP [0000-0001-5572-192X], Apollo - University of Cambridge Repository |
| Rok vydání: | 2019 |
| Předmět: |
3403 Macromolecular and Materials Chemistry
Materials science 34 Chemical Sciences General Chemical Engineering Oxide Ionic bonding 02 engineering and technology General Chemistry Nuclear magnetic resonance spectroscopy 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences chemistry.chemical_compound Solid-state nuclear magnetic resonance chemistry Chemical physics Bismuth vanadate Vacancy defect 3406 Physical Chemistry Materials Chemistry Fast ion conductor Ionic conductivity 0210 nano-technology |
| Zdroj: | Chemistry of materials, 2019, Vol.31(5), pp.1704-1714 [Peer Reviewed Journal] |
| Popis: | Ionic-conducting materials are crucial for the function of many advanced devices used in a variety of applications, such as fuel cells and gas separation membranes. Many different chemical controls, such as aliovalent doping, have been attempted to stabilise δ-Bi2O3, a material with exceptionally high oxide ion conductivity which is unfortunately only stable over a narrow temperature range. In this study, we employ a multinuclear, variable-temperature NMR spectroscopy approach to characterise and measure oxide ionic motion in the V- and P-substituted bismuth oxide materials Bi0.913V0.087O1.587, Bi0.852V0.148O1.648 and Bi0.852P0.148O1.648, previously shown to have excellent ionic conduction properties (Kuang et al., Chem. Mater. 2012, 24, 2162; Kuang et al., Angew. Chem. Int. Ed. 2012, 51, 690). Two main 17O NMR resonances are distinguished for each material, corresponding to O in the Bi–O and V–O/P–O sublattices. Using variable-temperature (VT) measurements ranging from room temperature to 923 K, the ionic motion experienced by these different sites has then been characterised, with coalescence of the two environments in the V-substituted materials clearly indicating a conduction mechanism facilitated by exchange between the two sublattices. The lack of this coalescence in the P-substituted material indicates a different mechanism, confirmed by 17O T1 (spin-lattice relaxation) NMR experiments to be driven purely by vacancy motion in the Bi–O sublattice. 51V and 31P VT-NMR experiments show high rates of tetrahedral rotation even at room temperature, increasing with heating. An additional VO4 environment appears in 17O and 51V NMR spectra of the more highly V-substituted Bi0.852V0.148O1.648, which we ascribe to differently distorted VO4 tetrahedral units that disrupt the overall ionic motion, consistent both with linewidth analysis of the 17O VT-NMR spectra and experimental results of Kuang et al. showing a lower oxide ionic conductivity in this material compared to Bi0.913V0.087O1.587 (Chem. Mater. 2012, 24, 2162). This study shows solid-state NMR is particularly well suited to understanding connections between local structural features and ionic mobility, and can quantify the evolution of oxide-ion dynamics with increasing temperature. |
| Databáze: | OpenAIRE |
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