Origin of the large strain response in (K{sub 0.5}Na{sub 0.5})NbO{sub 3}-modified (Bi{sub 0.5}Na{sub 0.5})TiO{sub 3}-BaTiO{sub 3} lead-free piezoceramics

Journal Article · Fri May 01 00:00:00 EDT 2009 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3121203· OSTI ID:21356145

Jo, Wook; Granzow, Torsten; Aulbach, Emil; Roedel, Juergen ^[1]; Damjanovic, Dragan ^[2]

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1. Institute of Materials Science, Technische Universitaet Darmstadt, 64287 Darmstadt (Germany)
2. Ceramics Laboratory, EPFL, Lausanne CH-1015 (Switzerland)

The mechanism of the giant unipolar strain recently observed in a lead-free piezoceramic, 0.92(Bi{sub 0.5}Na{sub 0.5})TiO{sub 3}-0.06BaTiO{sub 3}-0.02(K{sub 0.5}Na{sub 0.5})NbO{sub 3}[S.-T. Zhang, A. B. Kounga, E. Aulbach, H. Ehrenberg, and J. Roedel, Appl. Phys. Lett. 91, 112906 (2007) was investigated. The validity of the previously proposed mechanism that the high strain comes both from a significant volume change during the field-induced phase transition, from an antiferroelectric to a ferroelectric phase and the domain contribution from the induced ferroelectric phase was examined. Monitoring the volume changes from the simultaneously measured longitudinal and transverse strains on disk-shaped samples showed that the phase transition in this specific material does not involve any notable volume change, which indicates that there is little contribution from a volume change due to the phase transition to the total strain response. Temperature dependent hysteresis measurements on unpoled samples of a nearby ferroelectric composition, 0.93(Bi{sub 0.5}Na{sub 0.5})TiO{sub 3}-0.06BaTiO{sub 3}-0.01(K{sub 0.5}Na{sub 0.5})NbO{sub 3} demonstrated that the origin of the large strain is due to the presence of a nonpolar phase that brings the system back to its unpoled state once the applied electric field is removed, which leads to a large unipolar strain.

• OSTI ID: 21356145
• Journal Information: Journal of Applied Physics, Vol. 105, Issue 9; Other Information: DOI: 10.1063/1.3121203; (c) 2009 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

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