Coupling Between Octahedral Tilting and Ferroelectric Order in Tetragonal Tungsten Bronze-Structured Dielectrics

Published

February 19, 2017

Author(s)

Igor Levin, M Stennett, D I. Woodward, A R. West, I Reaney

Abstract

Strong coupling between local polar displacements and a commensurate octahedral tilting is proposed to explain the onset of classic ferroelectric behavior in tetragonal tungsten bronze-like dielectrics BaLaxNd1-xNb3Ti2O15. The ferroelectric phase transition is associated with a discontinuous non lock-in transformation of an incommensurate structure described by the wave vectors q1=( +?)(ao*+bo*), q2= co to a commensurate superstructure with q1= (ao*+bo*), q2= co*, where ao bo 12.4 and co 4 refer to an ideal tetragonal tungsten bronze cell. In a manner reminiscent of perovskite-like oxides, the driving force for commensurate tilting increases as the average ionic radius of the rare-earth ion decreases, and no classical ferroelectric transition is observed for compositions with x>0.75 which remain incommensurate and only exhibit relaxor behavior below room temperature.

Citation

Applied Physics Letters

Pub Type

Journals

Keywords

ferroelectrics, octahedral tilting, relaxor, tetragonal tungsten bronze

Citation

Levin, I. , Stennett, M. , Woodward, D. , West, A. and Reaney, I. (2017), Coupling Between Octahedral Tilting and Ferroelectric Order in Tetragonal Tungsten Bronze-Structured Dielectrics, Applied Physics Letters (Accessed December 13, 2024)