The Library
93Nb NMR and DFT investigation of the polymorphs of NaNbO3
Tools
Johnston, Karen E., Griffin, John M., Walton, Richard I., Dawson, Daniel M., Lightfoot, Philip and Ashbrook, Sharon E. (2011) 93Nb NMR and DFT investigation of the polymorphs of NaNbO3. Physical Chemistry Chemical Physics, Vol.13 (No.16). p. 7565. doi:10.1039/c1cp20258h ISSN 1463-9076.
Research output not available from this repository.
Request-a-Copy directly from author or use local Library Get it For Me service.
Official URL: http://dx.doi.org/10.1039/C1CP20258H
Abstract
Sodium niobate (NaNbO3) has a particularly complex phase diagram, with a series of phase transitions as a function of temperature and pressure, and even at room temperature a number of different structural variations have been suggested. Recent work has demonstrated that bulk powders of NaNbO3, prepared using a variety of synthetic approaches, contain a mixture of perovskite phases; the commonly reported Pbcm phase and a second, polar phase tentatively identified as belonging to space group P21ma. The two phases exhibit very similar 23Na MAS NMR spectra, although high-resolution MQMAS spectra were able to distinguish between them. Here, we investigate whether different perovskite polymorphs can be distinguished and/or identified using a variety of 93Nb NMR methods, including MAS, MQMAS and wideline experiments. We compare the experimental results obtained for these more common perovskite materials to those for the metastable ilmenite polymorph of NaNbO3. Our experimental results are supported by first-principles calculations of NMR parameters using a planewave pseudopotential approach. The calculated NMR parameters appear very different for each of the phases investigated, but high forces on the atoms indicate many of the structural models derived from diffraction require optimisation of the atomic coordinates. After geometry optimisation, most of these perovskite phases exhibit very similar NMR parameters, in contrast to recent work where it was suggested that 93Nb provides a useful tool for distinguishing NaNbO3 polymorphs. Finally, we consider the origin of the quadrupolar coupling in these materials, and its dependence on the deviation from ideality of the NbO6 octahedra.
Item Type: | Journal Article | ||||
---|---|---|---|---|---|
Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry | ||||
Journal or Publication Title: | Physical Chemistry Chemical Physics | ||||
Publisher: | Royal Society of Chemistry | ||||
ISSN: | 1463-9076 | ||||
Official Date: | 2011 | ||||
Dates: |
|
||||
Volume: | Vol.13 | ||||
Number: | No.16 | ||||
Page Range: | p. 7565 | ||||
DOI: | 10.1039/c1cp20258h | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published |
Data sourced from Thomson Reuters' Web of Knowledge
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |