Polymorphic Phase Transition and Domain Configurations of (K, Na)NbO3-Based Lead-Free Ceramics Modified by (Ba0.6Ca0.4)ZrO3

Abstract

In this work, (1−x)(K0.5Na0.5)(Nb0.96Sb0.04)−x(Ba0.6Ca0.4)ZrO3 lead-free piezoelectric ceramics were prepared by a conventional solid-state sintering method. The relationship between the composition, structure and performance of the system was analyzed specifically. A polymorphic phase transition with rhombohedral-tetragonal (R-T) was formed in the sample with x = 0.3 at the room temperature (∼27 °C), which was tested by X-ray diffraction (XRD) and the temperature-dependent dielectric behavior. The high-density polar nanodomain regions were observed through Transmission Electron Microscope (TEM) in the sample with x = 0.3. Thanks to the rotation of the domain and the movement of the domain wall, the piezoelectric performance was improved, the ceramics with x = 0.3 possess enhanced piezoelectric properties of d 33 ∼ 325 pC/N together with a high Curie temperature of T c ∼ 335 °C. Furthermore, the thermal stability in the sample with x = 0.3 can be enhanced to (Δd 33/Δd 33(25 °C) ∼ 12.54%), exhibiting good temperature stability, which guarantees the ceramics could be used in a wide temperature rage.