Emergent Low-Symmetry Phases and Large Property Enhancements in Ferroelectric KNbO 3 Bulk Crystals.

Autor: Lummen TTA; Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802, USA., Leung J; Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802, USA., Kumar A; School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast, BT71NN, Northern Ireland, UK., Wu X; Department of Physics, University of Texas at Austin, Austin, TX, 78712, USA., Ren Y; Department of Physics, University of Texas at Austin, Austin, TX, 78712, USA., VanLeeuwen BK; Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802, USA., Haislmaier RC; Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802, USA., Holt M; Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, 60439, USA., Lai K; Department of Physics, University of Texas at Austin, Austin, TX, 78712, USA., Kalinin SV; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA., Gopalan V; Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
Jazyk: angličtina
Zdroj: Advanced materials (Deerfield Beach, Fla.) [Adv Mater] 2017 Aug; Vol. 29 (31). Date of Electronic Publication: 2017 Jun 19.
DOI: 10.1002/adma.201700530
Abstrakt: The design of new or enhanced functionality in materials is traditionally viewed as requiring the discovery of new chemical compositions through synthesis. Large property enhancements may however also be hidden within already well-known materials, when their structural symmetry is deviated from equilibrium through a small local strain or field. Here, the discovery of enhanced material properties associated with a new metastable phase of monoclinic symmetry within bulk KNbO 3 is reported. This phase is found to coexist with the nominal orthorhombic phase at room temperature, and is both induced by and stabilized with local strains generated by a network of ferroelectric domain walls. While the local microstructural shear strain involved is only ≈0.017%, the concurrent symmetry reduction results in an optical second harmonic generation response that is over 550% higher at room temperature. Moreover, the meandering walls of the low-symmetry domains also exhibit enhanced electrical conductivity on the order of 1 S m -1 . This discovery reveals a potential new route to local engineering of significant property enhancements and conductivity through symmetry lowering in ferroelectric crystals.
(© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
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