Atomic structural mechanism for ferroelectric-antiferroelectric transformation in perovskite NaNbO 3
- City Univ. of Hong Kong (Hong Kong)
- City Univ. of Hong Kong (Hong Kong); Indian Inst. of Technology (IIT), Madras (India)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Aarhus Univ. (Denmark); Lund Univ. (Sweden)
- Univ. of Sydney, NSW (Australia)
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. In this work, 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 300 K ≤ 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.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE; Swedish Research Council (SRC); Vinnova; Swedish Research Council (SRC) (Formas); NUFI Grant
- Grant/Contract Number:
- AC05-00OR22725; 2018–07152; 2018–04969; 2019–02496; 4059-00009B; IPTS-27376
- OSTI ID:
- 1871099
- Journal Information:
- Physical Review. B, Vol. 105, Issue 17; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Uniform structural phase transition in
Local atomic and magnetic structure of multiferroic
Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
antiferroelectricity
electrical properties
phase transitions
structural properties
ferroelectrics
electronically polarized systems
perovskites
crystalline systems
crystal structures
neutron diffraction
neutron techniques
neutron pair-distribution function analysis
x-ray diffraction
x-ray techniques