Phase transitions and potential ferroelectricity in noncentrosymmetric KNaNbOF5

Jaye K. Harada, Po-Hsiu Chien, Haoyu Liu, Sawankumar Patel, Ching-Hwa A. Chen, Nenian Charles, Yan-Yan Hu, Kenneth R. Poeppelmeier, and James M. Rondinelli
Phys. Rev. Materials 5, 124401 – Published 1 December 2021
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Abstract

Increasing the number of known ferroelectrics requires expanding the chemical design space and mechanisms producing ferroelectricity. To that end, we examine the displacive, noncentrosymmetric-to-centrosymmetric phase transition in the oxyfluoride KNaNbOF5 using ab initio calculations and Landau theory. We predict an intermediate Pnma phase occurs in the transition from the known low- and high-temperature phases, Pna21 and Cmcm, respectively, which we subsequently confirm using high-resolution and in situ F19 magic-angle spinning nuclear magnetic resonance. Using the intermediate structure, we then calculate the monodomain polarization switching barrier in KNaNbOF5 to be 93 meV per formula unit, comparable to existing ferroelectrics. The reversal of the polarization is due to uncompensated antipolar displacements of oxygen and fluorine and does not require oxygen and fluorine site exchange as in other nonswitchable heteroanionic materials, which makes KNaNbOF5 a viable oxyfluoride for a switchable electric polarization.

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  • Received 2 August 2021
  • Accepted 10 November 2021

DOI:https://doi.org/10.1103/PhysRevMaterials.5.124401

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Jaye K. Harada1, Po-Hsiu Chien2,*, Haoyu Liu2, Sawankumar Patel2, Ching-Hwa A. Chen3, Nenian Charles4, Yan-Yan Hu2,5, Kenneth R. Poeppelmeier1,3, and James M. Rondinelli1,†

  • 1Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
  • 2Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA
  • 3Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
  • 4Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
  • 5Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA

  • *Present address: Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
  • jrondinelli@northwestern.edu

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Issue

Vol. 5, Iss. 12 — December 2021

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