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Ensemble-based modelling of the NMR spectra of solid solutions: cation disorder in Y2(Sn,Ti)2O7

Moran, R. F., McKay, D., Tornstrom, P. C., Aziz, A., Fernandez, A., Grau-Crespo, R. and Ashbrook, S. E. (2019) Ensemble-based modelling of the NMR spectra of solid solutions: cation disorder in Y2(Sn,Ti)2O7. Journal of the American Chemical Society, 141 (44). pp. 17838-17846. ISSN 1520-5126

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To link to this item DOI: 10.1021/jacs.9b09036

Abstract/Summary

The sensitivity of NMR to the local environment, without the need for any long-range order, makes it an ideal tool for the characterization of disordered materials. Computational prediction of NMR parameters can be of considerable help in the interpretation and assignment of NMR spectra of solids, but the statistical representation of all possible chemical environments for a solid solution is challenging. Here, we illustrate the use of a symmetry-adapted configurational ensemble in the simulation of NMR spectra, in combination with solid-state NMR experiments. We show that for interpretation of the complex and overlapped lineshapes that are typically observed, it is important to go beyond a single-configuration representation or a simple enumeration of local environments. The ensemble method leads to excellent agreement between simulated and experimental spectra for Y2(Sn,Ti)2O7 pyrochlore ceramics, where the overlap of signals from different local environments prevents a simple decomposition of the experimental spectral lineshapes. The inclusion of a Boltzmann weighting confirms that the best agreement with experiment is obtained at higher temperatures, in the limit of full disorder. We also show that to improve agreement with experiment, in particular at low dopant concentrations, larger supercells are needed, which might require alternative simulation approaches as the complexity of the system increases. It is clear that ensemble-based modeling approaches in conjunction with NMR spectroscopy offer great potential for understanding configurational disorder, ultimately aiding the future design of functional materials.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:86676
Uncontrolled Keywords:Site occupancy disorder; solid-state NMR spectroscopy; density functional theory; pyrochlores
Publisher:American Chemical Society

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