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Atomic structural mechanism for ferroelectric-antiferroelectric transformation in perovskite NaNbO3

Htet, Cho Sandar ; Nayak, S. ; Manjón-Sanz, Alicia ; Liu, J. ; Kong, J. ; Sørensen, D. R. LU orcid ; Marlton, F. ; Jørgensen, M. R.V. LU orcid and Pramanick, A. (2022) In Physical Review B 105(17).
Abstract

Sodium niobate (NaNbO3 or NN) is described as "the most complex perovskite system,"which exhibits transitions between, as well as coexistence of, several ferroelectrics (FE) and antiferroelectric (AFE) phases at different temperatures. Recently, solid solutions of NN with stabilized AFE phases(s) have gained attention for energy-related applications, such as high-density energy storage and electrocaloric cooling. A better understanding of the atomic mechanisms responsible for AFE/FE phase transitions in NaNbO3 can enable a more rational design of its solid-solution systems with tunable functional properties. Here, we have investigated changes in the average and local atomic structure of NN using a combination of... (More)

Sodium niobate (NaNbO3 or NN) is described as "the most complex perovskite system,"which exhibits transitions between, as well as coexistence of, several ferroelectrics (FE) and antiferroelectric (AFE) phases at different temperatures. Recently, solid solutions of NN with stabilized AFE phases(s) have gained attention for energy-related applications, such as high-density energy storage and electrocaloric cooling. A better understanding of the atomic mechanisms responsible for AFE/FE phase transitions in NaNbO3 can enable a more rational design of its solid-solution systems with tunable functional properties. Here, we have investigated changes in the average and local atomic structure of NN using a combination of x-ray/neutron diffraction and neutron pair-distribution function (PDF) analyses. The Rietveld refinement of the x-ray/neutron-diffraction patterns indicates a coexistence of the FE Q (P21ma) and AFE P (Pbma) phases in the temperature range of 300K≤T≤615K, while PDF analysis indicated that the local structure (r<8Å) is better described by a P21ma symmetry. Above 615 K, the average structure transitions to an AFE R phase (Pmmn or Pnma), while PDF analysis shows an increased disordering of the octahedral distortions and Na displacements at the local scale. These results indicate that the average P/Q/R phase transitions in NN can be described as a result of complex ordering of distorted octahedral tilts at the nanoscale and off-centered displacements of the Na atoms.

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B
volume
105
issue
17
article number
174113
pages
13 pages
publisher
American Physical Society
external identifiers
  • scopus:85131301014
ISSN
2469-9950
DOI
10.1103/PhysRevB.105.174113
language
English
LU publication?
yes
id
43f29b5d-4ef0-424f-9568-87d1c21b5c6b
date added to LUP
2022-08-22 12:02:35
date last changed
2022-08-24 10:57:09
@article{43f29b5d-4ef0-424f-9568-87d1c21b5c6b,
  abstract     = {{<p>Sodium niobate (NaNbO<sub>3</sub> or NN) is described as "the most complex perovskite system,"which exhibits transitions between, as well as coexistence of, several ferroelectrics (FE) and antiferroelectric (AFE) phases at different temperatures. Recently, solid solutions of NN with stabilized AFE phases(s) have gained attention for energy-related applications, such as high-density energy storage and electrocaloric cooling. A better understanding of the atomic mechanisms responsible for AFE/FE phase transitions in NaNbO<sub>3</sub> can enable a more rational design of its solid-solution systems with tunable functional properties. Here, we have investigated changes in the average and local atomic structure of NN using a combination of x-ray/neutron diffraction and neutron pair-distribution function (PDF) analyses. The Rietveld refinement of the x-ray/neutron-diffraction patterns indicates a coexistence of the FE <i>Q</i> (P2<sub>1</sub><i>ma</i>) and AFE P (Pb<i>ma</i>) phases in the temperature range of 300K≤<i>T</i>≤615K, while PDF analysis indicated that the local structure (<i>r</i>&lt;8Å) is better described by a P2<sub>1</sub><i>ma</i> symmetry. Above 615 K, the average structure transitions to an AFE <i>R</i> phase (<i>Pmmn</i> or <i>Pnma</i>), while PDF analysis shows an increased disordering of the octahedral distortions and Na displacements at the local scale. These results indicate that the average P/Q/R phase transitions in NN can be described as a result of complex ordering of distorted octahedral tilts at the nanoscale and off-centered displacements of the Na atoms. </p>}},
  author       = {{Htet, Cho Sandar and Nayak, S. and Manjón-Sanz, Alicia and Liu, J. and Kong, J. and Sørensen, D. R. and Marlton, F. and Jørgensen, M. R.V. and Pramanick, A.}},
  issn         = {{2469-9950}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{17}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review B}},
  title        = {{Atomic structural mechanism for ferroelectric-antiferroelectric transformation in perovskite NaNbO<sub>3</sub>}},
  url          = {{http://dx.doi.org/10.1103/PhysRevB.105.174113}},
  doi          = {{10.1103/PhysRevB.105.174113}},
  volume       = {{105}},
  year         = {{2022}},
}