A Numerical Investigation of the Effect of Induced Porosity on the Electromechanical Switching of Ferroelectric Ceramics

Abstract

Ferroelectric ceramics have many applications ranging from microelectromechanical systems (MEMS) to explosively driven power supplies. In addition to chemical compositions and processing methods, porosity is an important material parameter that can affect both the electrical and mechanical responses of a ferroelectric. The main objective of the current study is to gain preliminary insight on the possible effect of porosity on the switching behavior of ferroelectrics.

Numerical simulation was used to address the research objective. The numerical code used is an arbitrary Lagrangian-Eulerian, multi-material, multi-physics finite element code developed by Sandia National Laboratories. To accomplish the research objective, a phenomenological electromechanical model developed by Landis was first implemented in the code. The effects of void density, which ranges from 0 to 11%, and shape, which includes sphere and cylinder, were then investigated through a parametric study.

The study indicates that the remanent polarization decreases with increased porosity density. For a given density, the porous solid that contains the cylindrical voids whose longitudinal axis is perpendicular to the applied electric field possesses the largest amount of the remanent polarization. The solid that contains the cylindrical voids whose longitudinal axis is parallel to the applied electric field has the least while the one containing spherical voids is intermediate. It is conjectured that the void shape effect is mainly due to the fact that the void perturbs the distribution of electric field and polarization with respect to from the applied electric field direction and different shapes of void result in different degrees of perturbation.

The limitation of the current numerical simulation and possible future work are also discussed.

Keywords::

• Ferroelectric ceramic
• porosity
• electromechanical
• switching

VIII. ACKNOWLEDGMENTS

The authors would like to thank Sandia National Laboratories for their support for this work. J. L. Ding would also like to express his deep appreciation to Drs. John Aidun and Steve Montgomery at Sandia National Labs for their guidance and advice for this work.