Giant thermally-enhanced electrostriction and polar surface phase in La2Mo2O9 oxygen ion conductors

Li, Qian and Lu, Teng and Schiemer, Jason A. and Laanait, Nouamane and Balke, Nina and Zhang, Zhan and Ren, Yang and Carpenter, Michael A. and Wen, Haidan and Li, Jiangyu and Kalinin, Sergei V. and Liu, Yun (2018) Giant thermally-enhanced electrostriction and polar surface phase in La2Mo2O9 oxygen ion conductors. Physical Review Materials, 2 (4). ISSN 2475-9953 DOI https://doi.org/10.1103/PhysRevMaterials.2.041403

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Official URL: https://doi.org/10.1103/PhysRevMaterials.2.041403

Abstract

Ferroelectrics possess spontaneous electric polarization at macroscopic scales which nonetheless imposes strict limitations on the material classes. Recent discoveries of untraditional symmetry-breaking phenomena in reduced material dimensions have indicated feasibilities to extend polar properties to broader types of materials, potentially opening up the freedom for designing materials with hybrid functionalities. Here, we report the unusual electromechanical properties of La2Mo2O9 (LAMOX) oxygen ion conductors, systematically investigated at both bulk and surface length levels. We first observed giant electrostriction effects in La2Mo2O9 bulk ceramics that are thermally enhanced in concert with their low-energy oxygen-vacancy hopping dynamics. Moreover, while no clear bulk polarization was detected, the surface phases of LAMOX were found to be manifestly polar, likely originating from the coupling between the intrinsic structural flexibilities with strain gradients (i.e., flexoelectricity) and/or chemical heterogeneities present in the materials. These findings identify La2Mo2O9 as a promising electromechanical material system and suggest that the flexible structural and chemical configurations in ionically active materials could enable fundamentally different venues to accommodate electric polarization.

Item Type: Article
Uncontrolled Keywords: 2018AREP; IA76
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
08 - Green Open Access
Journal or Publication Title: Physical Review Materials
Volume: 2
Identification Number: https://doi.org/10.1103/PhysRevMaterials.2.041403
Depositing User: Sarah Humbert
Date Deposited: 23 Apr 2020 23:20
Last Modified: 23 Apr 2020 23:20
URI: http://eprints.esc.cam.ac.uk/id/eprint/4693

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