Levin, I., Yang, F., Maier, R. et al. (4 more authors) (2020) Displacive order–disorder behavior and intrinsic clustering of lattice distortions in bi‐substituted NaNbO3. Advanced Functional Materials, 30 (30). 2001840. ISSN 1616-301X
Abstract
Perovskite‐like NaNbO3‐Bi1/3NbO3 solid solutions are studied to understand the interactions between octahedral rotations, which dominate the structural behavior of NaNbO3 and displacive disorder of Bi present in Bi1/3NbO3. Models of instantaneous structures for representative compositions are obtained by refining atomic coordinates against X‐ray total scattering and extended X‐ray‐absorption fine structure data, with additional input obtained from transmission electron microscopy. A mixture of distinct cations and vacancies on the cuboctahedral A‐sites in Na1−3x Bix NbO3 (x ≤ 0.2) results in 3D nanoscale modulations of structural distortions. This phenomenon is determined by the inevitable correlations in the chemical composition of adjacent unit cells according to the structure type—an intrinsic property of any nonmolecular crystals. Octahedral rotations become suppressed as x increases. Out‐of‐phase rotations vanish for x > 0.1, whereas in‐phase tilts persist up to x = 0.2, although for this composition their correlation length becomes limited to the nanoscale. The loss of out‐of‐phase tilting is accompanied by qualitative changes in the probability density distributions for Bi and Nb, with both species becoming disordered over loci offset from the centers of their respective oxygen cages. Symmetry arguments are used to attribute this effect to different strengths of the coupling between the cation displacements and out‐of‐phase versus in‐phase rotations. The displacive disorder of Bi and Nb combined with nanoscale clustering of lattice distortions are primarily responsible for the anomalous broadening of the temperature dependence of the dielectric constant.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim. This is an author-produced version of a paper subsequently published in Advanced Functional Materials. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | dielectric; disorder; pair distribution functions; perovskites; solid solutions; X‐ray scattering |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Funding Information: | Funder Grant number ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/L027348/1 ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/L017563/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 15 Jul 2020 12:13 |
Last Modified: | 20 Jan 2022 13:43 |
Status: | Published |
Publisher: | Wiley |
Refereed: | Yes |
Identification Number: | 10.1002/adfm.202001840 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:163283 |