Na-23 multiple-quantum MAS NMR of the perovskites NaNbO3 and NaTaO3

Ashbrook, S. E. and Le Polles, L. and Gautier, R. and Pickard, C. J. and Walton, R. I. (2006) Na-23 multiple-quantum MAS NMR of the perovskites NaNbO3 and NaTaO3. Physical Chemistry Chemical Physics, 8 (29). pp. 3423-3431. DOI 10.1039/B604520K

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Abstract

The distorted perovskites NaTaO3 and NaNbO3 have been studied using 23Na multiple-quantum (MQ) MAS NMR. NaTaO3 was prepared by high temperature solid state synthesis and the NMR spectra are consistent with the expected room temperature structure of the material (space group Pbnm), with a single crystallographic sodium site. Two samples of NaNbO3 were studied. The first, a commercially available sample which was annealed at 900 °C, showed two crystallographic sodium sites, as expected for the room temperature structure of the material (space group Pbcm). The second sample, prepared by a low temperature hydrothermal method, showed the presence of four sodium sites, two of which match the expected room temperature structure and the second pair, another polymorph of the material (space group P21ma). This is consistent with powder X-ray diffraction data which showed weak extra peaks which can be accounted for by the presence of this second polymorph. Density functional theory (DFT) calculations support our conclusions, and aid assignment of the NMR spectra. Finally, we discuss the measured NMR parameters in relation to other studies of sodium in high coordination sites in the solid state.

Item Type: Article
Uncontrolled Keywords: 2006 AREP 2006 P IA52
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Physical Chemistry Chemical Physics
Volume: 8
Page Range: pp. 3423-3431
Identification Number: 10.1039/B604520K
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:01
Last Modified: 11 Apr 2014 09:35
URI: http://eprints.esc.cam.ac.uk/id/eprint/121

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