Layered Relaxor-Ferroelectric composite has been shown experimentally to be able to enhance large-signal response d33 in lead-free ceramics, for instance by Zhang et al.. [1] The enhancement of the d33 is found at some specific ratio of each component. The underlying mechanism of the abnormal behavior in the layered structure is elucidated as the strain coupling effect accompanied with polarization coupling effect between the layers. In this presentation, two approaches are established to investigate the coupling effect of the Relaxor-Ferroelectric layered structure. In the analytical approach, two criteria are given independently for the serial layered model, i.e., polarization equality condition by which only the polarization coupling effect is included, and strain equality condition by which only the strain coupling effect is included. The typical hysteresis loops, such as P-E loops and S-E loops of the composite can be calculated by the hysteresis loops of each component. In the phase-field approach, the detailed polarization and strain distribution in relaxor layer and ferroelectric layer can be calculated by our previous random field model. [2] Both polarization and strain coupling effect are intrinsically included in the model. Two lead-free material systems are used, and the enhancement of the d33 is observed.
The work of Shuai Wang is supported by the 'Excellence Initiative' of the German Federal and State Governments and the Graduate School of Computational Engineering at Technische Universität Darmstadt.
References
[1] H. Zhang, C. Groh, Q. Zhang, et al. Advanced Electronic Materials, 1-6 (2015).
[2] S. Wang, M. Yi and B.-X. Xu, International Journal of Solids and Structures, 83, 142-153 (2016).