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dc.contributor.authorFernandes, Arantxa
dc.contributor.authorMoran, Robert F
dc.contributor.authorMcKay, David
dc.contributor.authorGriffiths, Ben
dc.contributor.authorHerlihy, Anna
dc.contributor.authorWhittle, Karl R
dc.contributor.authorDawson, Daniel McLean
dc.contributor.authorAshbrook, Sharon E.
dc.identifier.citationFernandes , A , Moran , R F , McKay , D , Griffiths , B , Herlihy , A , Whittle , K R , Dawson , D M & Ashbrook , S E 2021 , ' Exploring cation disorder in mixed-metal pyrochlore ceramics using 17 O NMR spectroscopy and first-principles calculations ' , Magnetic Resonance in Chemistry , vol. 59 , no. 9-10 .
dc.identifier.otherPURE: 272742886
dc.identifier.otherPURE UUID: 7b871cb3-718a-4c97-b06b-5e91b721ea4d
dc.identifier.otherORCID: /0000-0002-4538-6782/work/89178316
dc.identifier.otherORCID: /0000-0002-8110-4535/work/89178336
dc.identifier.otherScopus: 85100833615
dc.identifier.otherWOS: 000617935700001
dc.descriptionFunding: Royal Society (Grant Number(s): Wolfson Merit Award); FP7 Ideas: European Research Council (Grant Number(s): 614290); Engineering and Physical Sciences Research Council (Grant Number(s): EP/M022501/1).en
dc.description.abstractCharacterising the local structures (e.g., the cation distribution) of mixed-metal ceramics by NMR spectroscopy is often challenging owing to the unfavourable properties (low γ, large quadrupole moment and/or low abundance) of many metal nuclei. 17O is an attractive option owing to the prevalence of oxygen within ceramics. The moderate γ and small quadrupole moment of 17O mean that the greatest barrier to accessing the information available from this nucleus is isotopic enrichment. We explore the challenges of ensuring uniform isotopic enrichment with 17O2(g) for the pyrochlore solid solutions, Y2SnxTi2–xO7, La2SnxZr2–xO7 and La2SnxHf2–xO7, demonstrating that high enrichment temperatures (900 °C for 12 h) are required. In addition, for sites with very high symmetry (such as the tetrahedral OY4 and OLa4 sites with CQ ≈ 0 present here), we demonstrate that quantitative 17O NMR spectra require correction for the differing contributions from the centreband of the satellite transitions, which can be as high as a factor of ~3.89. It is common to use first-principles calculations to aid in interpreting NMR spectra of disordered solids. Here, we use an ensemble modelling approach to ensure that all possible cation arrangements are modelled in the minimum possible number of calculations. By combining uniform isotopic enrichment, quantitative NMR spectroscopy and a comprehensive computational approach, we are able to show that the cation distribution in Y2SnxTi2–xO7 is essentially random, whereas in La2SnxZr2–xO7 and La2SnxHf2–xO7, OLa2SnZr and OLa2SnHf sites are slightly energetically disfavoured, leading to a weak preference for clustering of like cations.
dc.relation.ispartofMagnetic Resonance in Chemistryen
dc.rightsCopyright © 2021 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.en
dc.subjectQD Chemistryen
dc.subjectTK Electrical engineering. Electronics Nuclear engineeringen
dc.titleExploring cation disorder in mixed-metal pyrochlore ceramics using 17O NMR spectroscopy and first-principles calculationsen
dc.typeJournal articleen
dc.contributor.sponsorEuropean Research Councilen
dc.contributor.sponsorThe Royal Societyen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. School of Chemistryen
dc.contributor.institutionUniversity of St Andrews. EaSTCHEMen
dc.description.statusPeer revieweden
dc.identifier.grantnumber614290 - EXONMRen

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