| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Dawson, Daniel M.
University of St Andrews
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (15/15 displayed)
- 2024Site-directed cation ordering in chabazite-type Al x Ga 1–x PO 4 -34 frameworks revealed by NMR crystallographycitations
- 2024Site-directed cation ordering in chabazite-type AlxGa1–xPO4-34 frameworks revealed by NMR crystallographycitations
- 2024Site-directed cation ordering in chabazite-type Al x Ga 1− x PO 4 -34 frameworks revealed by NMR crystallographycitations
- 2024Site-directed cation ordering in chabazite-type AlxGa1−xPO4-34 frameworks revealed by NMR crystallographycitations
- 2023Synthesis of FeAPO-34 molecular sieve under ionothermal conditioncitations
- 2022Synthesis of FeAPO-34 molecular sieve under ionothermal conditioncitations
- 201817 O solid-state NMR spectroscopy of A 2 B 2 O 7 oxides:quantitative isotopic enrichment and spectral acquisition?citations
- 201817O solid-state NMR spectroscopy of A2B2O7 oxidescitations
- 2017A gel aging effect in the synthesis of open-framework gallium phosphatescitations
- 2017Assembly-diassembly-organization-reassembly synthesis of zeolites based on cfi-type layerscitations
- 2016Phase Composition and Disorder in La2(Sn,Ti)2O7 Ceramics: New Insights from NMR Crystallography
- 2016Phase composition and disorder in La2(Sn,Ti)2O7 ceramicscitations
- 2015Combined theoretical and experimental investigations of porous crystalline materials
- 2011A co-templating route to the synthesis of Cu SAPO STA-7, giving an active catalyst for the selective catalytic reduction of NO
- 2011A co-templating route to the synthesis of Cu SAPO STA-7, giving an active catalyst for the selective catalytic reduction of NOcitations
Places of action
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article
Phase composition and disorder in La2(Sn,Ti)2O7 ceramics
Abstract
An NMR crystallographic approach, involving the combination of <sup>119</sup>Sn NMR spectroscopy, XRD and DFT calculations, is demonstrated for the characterisation of La<sub>2</sub>Sn<sub>2–x</sub>Ti<sub>x</sub>O<sub>7</sub> ceramics. A phase change from pyrochlore (La<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>) to a layered perovskite phase (La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>) is predicted (by radius ratio rules) to occur when x ≈ 0.95. However, the sensitivity of NMR spectroscopy to the local environment is able to reveal a significant two-phase region is present, extending from x = 1.8 to ~0.2, with limited solid solution at the two extremes, in broad agreement with powder XRD measurements. DFT calculations reveal that there is preferential site substitution of Sn in La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>, with calculated shifts for Sn substitution onto Ti1 and Ti2 sites (in the “bulk” perovskite layers) in better agreement with experiment than those for Ti3 and Ti4 (“edge” sites). Substitution onto these two sites also produces structural models with lower relative enthalpy. As the Sn content decreases, there is a further preference for substitution onto Sn2. In contrast, the relative intensities of the spectral resonances suggest that Ti substitution into the pyrochlore phase is random, although only a limited solid solution is observed (up to ~7% Ti). DFT calculations predict very similar <sup>119</sup>Sn shifts for Sn substitution into the two proposed models of La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> (monoclinic (P2<sub>1</sub>) and orthorhombic (Pna2<sub>1</sub>)), indicating it is not possible to distinguish between them. However, the relative energy of the Sn-substituted orthorhombic phase was higher than that of substituted monoclinic cells, suggesting that the latter is the more likely structure.