DOI: 10.1126/science.1177046 ISSN:

A Strain-Driven Morphotropic Phase Boundary in BiFeO 3

R. J. Zeches, M. D. Rossell, J. X. Zhang, A. J. Hatt, Q. He, C.-H. Yang, A. Kumar, C. H. Wang, A. Melville, C. Adamo, G. Sheng, Y.-H. Chu, J. F. Ihlefeld, R. Erni, C. Ederer, V. Gopalan, L. Q. Chen, D. G. Schlom, N. A. Spaldin, L. W. Martin, R. Ramesh
  • Multidisciplinary
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Biffed into Shape

BiFeO 3 is known to have a very large ferroelectric polarization. Although the bulk ground state is rhombohedral (with the electrical polarization along the [111] direction), in thin films and under epitaxial strain, the material can be tetragonally distorted (polarization along [001]). Zeches et al. (p. 977 ) show that under compressive strain, these films are monoclinic, a phase that is highly stable because it comprises the same symmetry as the monoclinic phase which has been reported at the so-called morphotropic phase boundaries in technologically important ferroelectrics. This work offers the possibility of obtaining large piezoelectric responses in lead-free systems.

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