| 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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Ashbrook, Sharon. E.
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 AlxGa1–xPO4-34 frameworks revealed by NMR crystallographycitations
- 2024In situ single-crystal X-ray diffraction studies of physisorption and chemisorption of SO2 within a metal-organic framework and its competitive adsorption with watercitations
- 202313C pNMR shifts of MOFs based on Cu(II)-paddlewheel dimers - DFT predictions for spin-½ defectscitations
- 2022Synthesis of FeAPO-34 molecular sieve under ionothermal conditioncitations
- 2019Visualization of the effect of additives on the nanostructures of individual bio-inspired calcite crystalscitations
- 201817O solid-state NMR spectroscopy of A2B2O7 oxidescitations
- 2017A gel aging effect in the synthesis of open-framework gallium phosphatescitations
- 2016Phase composition and disorder in La2(Sn,Ti)2O7 ceramicscitations
- 2015New insights into phase distribution, phase composition and disorder in Y2(Zr,Sn)2O7 ceramics from NMR spectroscopycitations
- 2015Peri-substituted phosphorus-tellurium systems – an experimental and theoretical investigation of the P∙∙∙Te through-space interactioncitations
- 2013Color and Brightness Tuning in Heteronuclear Lanthanide Terephthalate Coordination Polymerscitations
- 2013Unusual Phase Behavior in the Piezoelectric Perovskite System, LixNa1-xNbO3citations
- 2013Structural study of La1-xYxScO3, combining neutron diffraction, solid-state NMR, and first-principles DFT calculationscitations
- 2011A co-templating route to the synthesis of Cu SAPO STA-7, giving an active catalyst for the selective catalytic reduction of NOcitations
- 2009Multinuclear Magnetic Resonance and DFT Studies of the Poly(chlorotrifluoroethylene-alt-ethyl vinyl ether) Copolymerscitations
Places of action
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article
17O solid-state NMR spectroscopy of A2B2O7 oxides
Abstract
The potential of <sup>17</sup>O NMR spectroscopy for the investigation of A<sub>2</sub>B<sub>2</sub>O<sub>7</sub> ceramic oxides important in the encapsulation of radioactive waste, is demonstrated, with post-synthetic enrichment by exchange with <sup>17</sup>O<sub>2</sub> gas. For Y<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>, Y<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> and La<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub> pyrochlores, enrichment of the two distinct O species is clearly non quantitative at lower temperatures (~700 °C and below) and at shorter times, despite these being used in prior work, with preferential enrichment of OA<sub>2</sub>B<sub>2</sub> favoured over that of OA<sub>4</sub>. At higher temperatures, the <sup>17</sup>O NMR spectra suggest that quantitative enrichment has been achieved, but the integrated signal intensities do not reflect the crystallographic 1:6 (O1:O2) ratio until corrected for differences in T<sub>1</sub> relaxation rates and, more importantly, the contribution of the satellite transitions. <sup>17</sup>O NMR spectra of Y<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> and Y<sub>2</sub>Hf<sub>2</sub>O<sub>7</sub> defect fluorites showed little difference with any variation in enrichment temperature or time, although an increase in the absolute level of enrichment (up to ~7.5%) was observed at higher temperature. DFT calculations show that the six distinct resonances observed cannot be assigned unambiguously, as each has contributions from more than one of the five possible next nearest neighbour environments. For La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>, which adopts a layered perovskite-like structure, little difference in the spectral intensities is observed with enrichment time or temperature, although the highest absolute levels of enrichment (~13%) were obtained at higher temperature. This work demonstrates that <sup>17</sup>O NMR has the potential to be a powerful probe of local structure and disorder in oxides, but that considerable care must be taken both in choosing the conditions for <sup>17</sup>O enrichment and the experimental acquisition parameters if the necessary quantitative measurements are to be obtained for more complex systems.