Competing Polar and Antipolar Structures in the Ruddlesden-Popper Layered Perovskite Li2SrNb2O7

Published

June 25, 2019

Author(s)

Ritesh Uppuluri, Hirofumi Akamatsu, Arnab Sen Gupta, Huaiyu Wang, Craig Brown, Kleyser E. Agueda Lopez, Nasim Alem, Venkatraman Gopalan, Thomas E. Mallouk

Abstract

Over the past few years, several studies have reported the existence of polar phase in n=2 Ruddlesden-Popper layer perovskites by trilinear coupling of oxygen octahedral rotations (OOR) and polar distortions, a phenomenon termed as hybrid improper ferroelectricity. This phenomenon has opened an avenue to expand the available compositions of ferroelectric and piezoelectric layered oxides. In this study, we report a new polar n=2 Ruddlesden-Popper layered niobate, Li₂SrNb₂O₇, which undergoes a structural transformation to an antipolar phase when cooled to 90 K. This structural transition results from a change in the phase of rotation of the octahedral layers within the perovskite slabs across the interlayers. First-principles calculations predicted that the antipolar Pnam phase would compete with the polar a2_1am phase and that both would be energetically lower than the previously assigned centrosymmetric Amam phase. This phase transition was experimentally observed by a combination of synchrotron X-ray diffraction, powder neutron diffraction, electrical and non-linear optical characterization techniques. The competition between symmetry breaking to yield polar layer perovskites and hybrid improper antiferroelectrics provides new insight into the rational design of antiferroelectric materials that can have applications as supercapacitors for energy storage.

Citation

Chemistry of Materials

Volume

31

Issue

12

Pub Type

Journals

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Keywords

polar, niobate, improper ferroelectricity, Crystsl structure

Citation

Uppuluri, R. , Akamatsu, H. , Gupta, A. , Wang, H. , Brown, C. , Agueda Lopez, K. , Alem, N. , Gopalan, V. and Mallouk, T. (2019), Competing Polar and Antipolar Structures in the Ruddlesden-Popper Layered Perovskite Li₂SrNb₂O₇, Chemistry of Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=927660 (Accessed October 15, 2025)