Summary: Imprint in ferroelectric materials due to space charges: A theoretical
M. B. Okatan and S. P. Alpaya
Department of Chemical, Materials, and Biomolecular Engineering, Materials Science and Engineering
Program, and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269,
Received 10 June 2009; accepted 15 August 2009; published online 1 September 2009
Imprint is a degradation mechanism in ferroelectrics that results in the displacement of the
polarization hysteresis loop along the electric field axis. We develop a model using a nonlinear
thermodynamic analysis coupled with electrostatics to show that such internal voltage offsets can
originate from asymmetrically distributed trapped space charges. The electrostatic interactions are
established through a built-in polarization due to the space charges and the spontaneous polarization.
Numerical results for Ba0.8Sr0.2TiO3 show that the maximum electric field offset does not
necessarily occur due to charges trapped near the electrodes. © 2009 American Institute of Physics.
Ferroelectrics possess a switchable nonzero polarization
that makes it possible for these materials to be used in non-
volatile memory applications. Furthermore, ferroelectrics can
sense changes in temperature, electric field, and stress state.
Therefore, these materials can be employed in a variety of