Suppressed dependence of polarization on epitaxial strain in highly polar ferroelectrics.
A combined experimental and computational investigation of coupling between polarization and epitaxial strain in highly polar ferroelectric PbZr(0.2)Ti(0.8)O3 (PZT) thin films is reported. A comparison of the properties of relaxed (tetragonality c/a approximately 1.05) and highly strained (c/a approximately 1.09) epitaxial films shows that polarization, while being amongst the highest reported for PZT or PbTiO3 in either film or bulk forms P(r) approximately 82 microC/cm(2)), is almost independent of the epitaxial strain. We attribute this behavior to a suppressed sensitivity of the A-site cations to epitaxial strain in these Pb-based perovskites, where the ferroelectric displacements are already large, contrary to the case of less polar perovskites, such as BaTiO3. In the latter case, the A-site cation (Ba) and equatorial oxygen displacements can lead to substantial polarization increases.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA. hnlee@ornl.gov
Ho Nyung
HN
Lee
Serge M
SM
Nakhmanson
Matthew F
MF
Chisholm
Hans M
HM
Christen
Karin M
KM
Rabe
David
D
Vanderbilt