Electric-field-induced strain of (Li,Na,K)NbO3-based multilayered piezoceramics under electromechanical loading

Lead-free (Li,Na,K)NbO3-based multilayered piezoceramics were prepared, and their large-signal piezoelectric properties, under combined electrical and mechanical loadings, were characterized from 25 °C to 100 °C. Under zero stress, the multilayer exhibited a high large-signal piezoelectric constant d 33 ∗ ( = S max / E max ) ≈ 350 pm/V with an applied unipolar field of 6 kV/mm. The stress-dependent d 33 ∗, with a unipolar field of 6 kV/mm, featured a pronounced sensitivity to the electric field with an evolving peak at −80 MPa, which was not observed at 100 °C. The disappearance of the evolving peak with increasing temperature suggests a strong influence of the crystallographic phase on the electromechanical properties of (Li,Na,K)NbO3-based multilayers. Further investigations of the stress–strain loop and stress–polarization change revealed that the field-dependent peak below 100 °C was due to the non-180° domain orientation induced by the combined electric field and compressive stress.