Electromechanical loading behaviors of barium titanate single crystals in the non-variant (110) direction
Date Issued
2011
Date
2011
Author(s)
Lin, Yen-Nan
Abstract
Strain behavior of barium titanate (BaTiO3) single crystals under combined electrical and mechanical loading in non-variant (110) direction is studied. A maximum strain of 0.2 % is obtained on BaTiO3 single crystals under a compressive stress of 3.03 MPa and a cyclic electric field of ±1.25 MVm-1, both applied in the (110) direction at room temperature. In contrast, when the external electrical and mechanical loading is applied at 55 °C, a maximum strain of 0.19 % is obtained when the compressive stress is increased to 11.85 MPa. This difference is believed to be caused by the variation in the magnitude of depolarization field at two temperatures. This study demonstrates that the enhancement of electrostrain in BaTiO3 single crystals can be achieved by applying a bias-stress even if the loading is in a non-variant direction.
To compare with the experimental data, the polarization and stain hystereses of BaTiO3 single crystals with electromechanical loading in the (110) direction at room temperature and 55 °C are simulated using the multirank laminate model. The parameters required for modeling, such as the starting and finishing electrical fields for the in-plane and out-of-plane 90° domain switchings, are obtained from in-situ domain observations using optical microscopy. By examining the experimental and modeling results, it is concluded that for BaTiO3 single crystals loaded in the (110) direction, the magnitude of depolarization field and the extent of in-plane 90° switching are the key factors governing the effectiveness of bias-stress on the enhancement of electrostrain.
The strain characteristics of linear PZT stack actuators under combined electrical and mechanical loading are also investigated in this study. It is found that the most effective way to increase the linear strain (i.e., piezoelectric strain) is by applying the bias-stress perpendicular to the electric field. This is caused by the further alignment of electrical dipoles in the electric field direction due to the applied stress.
Subjects
Barium titanate
Single crystal
Variant
Electromechanical loading
Domain switching
Multirank laminates
Stack actuator
Type
thesis
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