Large field-induced strains in a lead-free piezoelectric material
Zhang, J.X., B. Xiang, Q. He, J. Seidel, R.J. Zeches, P. Yu, S.Y. Yang, C.H. Wang, Y.-H. Chu, L.W. Martin, A.M. Minor, Ramamoorthy Ramesh
Piezoelectric materials exhibit a mechanical response to electrical inputs, as well as an electrical response to mechanical inputs, which makes them useful in sensors and actuators1. Lead-based piezoelectrics demonstrate a large mechanical response, but they also pose a health risk2. The ferroelectric BiFeO3 is an attractive alternative because it is lead-free, and because strain can stabilize BiFeO3 phases with a structure that resembles a morphotropic phase boundary3. Here we report a reversible electric-field-induced strain of over 5% in BiFeO 3 films, together with a characterization of the origins of this effect. In situ transmission electron microscopy coupled with nanoscale electrical and mechanical probing shows that large strains result from moving the boundaries between tetragonal- and rhombohedral-like phases, which changes the phase stability of the mixture. These results demonstrate the potential of BiFeO3 as a substitute for lead-based materials in future piezoelectric applications. © 2011 Macmillan Publishers Limited. All rights reserved.
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